Brachycephalic Airway Obstruction Syndrome (BAOS)
in the Cavalier King Charles Spaniel

Brachycephalic Airway Syndrome: Pathophysiology and Diagnosis. Dena L. Lodato, Cheryl S. Hedlund. Compendium. July 2012; 34(7).

Brachycephalic Airway Syndrome: Management. Dena L. Lodato, Cheryl S. Hedlund. Compendium. Aug 2012; 34(8). 

Variation of BMP3 Contributes to Dog Breed Skull Diversity. Jeffrey J. Schoenebeck, Sarah A. Hutchinson, Alexandra Byers, Holly C. Beale, Blake Carrington, Daniel L. Faden, Maud Rimbault, Brennan Decker, Jeffrey M. Kidd, Raman Sood, Adam R. Boyko, John W. Fondon, III, Robert K. Wayne, Carlos D. Bustamante, Brian Ciruna, Elaine A. Ostrander. PLoS Genet. 2012 August; 8(8): e1002849. Quote: "As a result of selective breeding practices, modern dogs display a multitude of head shapes. Breeds such as the Pug and Bulldog popularize one of these morphologies, termed “brachycephaly.” A short, upward-pointing snout, a massive and rounded head, and an underbite typify brachycephalic breeds. Here, we have coupled the phenotypes collected from museum skulls with the genotypes collected from dogs and identified five regions of the dog genome that are associated with canine brachycephaly [including the cavalier King Charles spaniel]. Fine mapping at one of these regions revealed a causal mutation in the gene BMP3. Bmp3's role in regulating cranial development is evolutionarily ancient, as zebrafish require its function to generate a normal craniofacial morphology. Our data begin to expose the genetic mechanisms unknowingly employed by breeders to create and diversify the cranial shape of dogs."

Do dog owners perceive the clinical signs related to conformational inherited disorders as ‘normal’ for the breed? A potential constraint to improving canine welfare. (Owner recognition of breathing disorders in brachycephalic dogs). RMA Packer, A Hendricks and CC Burn. Animal Welfare. 2012;21(S1):81-93. Quote: "Selection for brachycephalic (foreshortened muzzle) phenotypes in dogs is a major risk factor for brachycephalic obstructive airway syndrome (BOAS). Clinical signs include respiratory distress, exercise intolerance, upper respiratory noise and collapse. Efforts to combat BOAS may be constrained by a perception that it is ‘normal’ in brachycephalic dogs. This study aimed to quantify ownerperception of the clinical signs of BOAS as a veterinary problem. A questionnaire-based study was carried out over five months on the owners of dogs referred to the Queen Mother Hospital for Animals (QMHA) for all clinical services, except for Emergency and Critical Care. Owners reported the frequency of respiratory difficulty and characteristics of respiratory noise in their dogs in four scenarios, summarised as an ‘owner-reported breathing’ (ORB) score. Owners then reported whether their dog currently has, or has a history of, ‘breathing problems’. Dogs (n = 285) representing 68 breeds were included, 31 of which were classed as ‘affected’ by BOAS either following diagnostics, or by fitting case criteria based on their ORB score, skull morphology and presence of stenotic nares. The median ORB score given by affected dogs’ owners was 20/40 (range 8–30). Over half (58%) of owners of affected dogs reported that their dog did not have a breathing problem. This marked disparity between owners’ reports of frequent, severe clinical signs and their perceived lack of a ‘breathing problem’ in their dogs is of concern. Without appreciation of the welfare implications of BOAS, affected but undiagnosed dogs may be negatively affected indefinitely through lack of treatment. Furthermore, affected dogs may continue to be selected in breeding programmes, perpetuating this disorder."

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2013

Stop brachycephalism, now! Fraser Hale. Can.Vet.J. Feb. 2013;54(2):185-186. Quote: "In many Canadian jurisdictions, veterinarians have advocated for and achieved a ban on tail-docking, ear-cropping, and dewclaw removal as these are considered unnecessary cosmetic procedures that cause (temporary) pain with no benefit to the animals. I believe that as protectors of animal welfare, veterinarians should start a public awareness campaign to inform people of the serious, life-long negative impacts of brachycephalism. I believe we must stop referring to these conditions as 'normal for the breed' and refer to them as 'grossly abnormal in accordance with breed standards' because there is nothing re2013but comical breeds in advertising and promotional materials as this just increases public demand because they are 'so cute.'"

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2014

Laryngeal Disease in Dogs and Cats. Catriona MacPhail. Vet. Clinics of N.A.: Sm. Anim. Prac. Jan. 2014;44(1):19-31. Quote: "Brachycephalic airway syndrome refers to the condition of obstructive airway distress attributable to anatomic abnormalities of breeds such as English and French bulldogs, pugs, Boston terriers, and Cavalier King Charles spaniels."

Assoziation zephalometrischer Parameter mit dem Auftreten der Syringomyelie beim Cavalier King Charles Spaniel mit Chiari-ähnlicher Malformation [Association of anatomical parameters with the occurrence of syringomyelia in the Cavalier King Charles Spaniel with Chiari malformation]. Annabell Johanna Grübmeyer. Giessener Elektronische Bibliothek. Jan. 2014. Quote: "Until now the Chiari-like malformation was only diagnosed in brachycephalic dog breeds. Based on the decreased length-breadth ratio of its skull the Cavalier King Charles Spaniel can be classified as a highly brachycephalic dog. Therefore it could be assumed that the grade of brachycephaly is a pathophysiological factor for the development of syringomyelia and a retarded length growth of the skull might be the cause for the changes found in the Chiari-like malformation. The question is, if a shortening of the cranial base gives rise to the pathological changes in Chiari-like malformation. Based on this question we examined the anatomical parameters of 107 Cavalier King Charles Spaniels in relationship to the occurrence of syringomyelia. The study should give information about the pathogenesis of the Chiari-like malformation and the development of syringomyelia and if there is a difference in the cranial base length in Cavalier King Charles Spaniels with or without syringomyelia. The 107 Cavalier King Charles Spaniels examined in this study were mostly presented for breeding examinations, but some were also presented because of clinical signs. The age of the examined dogs ranged from 6 month to 9 years. We performed computed tomography of the skull and magnetic resonance imaging of the skull and spine of all patients. The examination of the spine in patients introduced for breeding examinations, were performed until the 5th cervical vertebra. In patients with neurological signs the examination included also the caudal cervical, thoracic and lumbar spine. Changes consistent with the Chiari-like malformation were found in all 107 Cavalier King Charles Spaniels. 63 of the 107 dogs showed a syringomyelia at the point of examination. The results of the study showed that the incidence of syringomyelia is correlated to the variables age (p less than 0,007), SBI [skull base index] (p less than 0,0192), PI [presphenoid index] (p less than 0,0447) and BI [basisphenoid index]  (p less than 0,0206). Furthermore it is shown that Cavalier King Charles Spaniels with a decrease in SBI have an increased risk to develop syringomyelia (odds ratio 1,26). In addition also the presphenoid and the basioccipital bone showed a reduced length, with an increase in breadth in dogs with syringomyelia. This study showed, that a reduced length of the cranial base represents a risk factor for the occurrence of syringomyelia. These results support the assumption of other authors that the cause of the Chiari-like malformation and syringomyelia is up to a growth disturbance of the cranial base."

Tracheal Collapse in Dogs. Mary Dell Deweese, Karen M. Tobias. Clinicians Brief. May 2014;83-87.

Evaluation of a novel tracheal stent for the treatment of tracheal collapse in dogs. D. Clarke, E. de Madron, R. Presley. J.Vet.Int.Med. July 2014;28(4):1364. Quote: "The purpose of this study was to evaluate the safety, efficacy, and satisfaction associated with a novel variable diameter tracheal stent designed specifically for canine anatomy and tracheal collapse. This was a multicenter retrospective study of 27 consecutive cases of tracheal collapse treated with the stent. Data forms requiring chart review and client interviews were distributed to the veterinarian placing each stent. Information was collected that compared symptoms pre- and post-stenting as well as a number of other parameters relating to the procedure and subsequent clinical course to assess stent performance and ease of use. Symptoms were graded on a visual line scale of 0-10. Paired t-tests or sign rank tests were used to determine changes in symptoms following stenting. A two-sided p-value of <0.05 was considered statistically significant. Responses were obtained from 20 of 27 cases. Data was normally distributed. The mean duration of follow-up was 3 months (range >1 to 17 months). There were no procedural complications. Operative mortality was 0%. There were no stent fractures or stent related deaths; symptomatic granulation tissue developed in one case. Statistically significant improvement was seen in cough, respiratory function, quality of life, and exercise tolerance. All veterinarians stated they would use the stent again. 95% of clients would repeat the procedure and 90% expressed satisfaction with the outcome. Tracheal stenting performed with the novel implant is both safe and subjectively effective in significantly improving clinical symptoms. Veterinarians and clients expressed a positive perception regarding outcomes associated with the stent."

Introducing breathlessness as a significant animal welfare issue. Beausoleil N, Mellor D. N.Z.Vet.J. July 2014;8:1-22. Quote: "Breathlessness is a negative affective experience relating to respiration, the animal welfare significance of which has largely been underestimated in the veterinary and animal welfare sciences. In this review, we draw attention to the negative impact that breathlessness can have on the welfare of individual animals and to the wide range of situations in which mammals may experience breathlessness. At least three qualitatively distinct sensations of breathlessness are recognised in human medicine - respiratory effort, air hunger and chest tightness - and each of these reflects comparison by cerebral cortical processing of some combination of heightened ventilatory drive and/or impaired respiratory function. Each one occurs in a variety of pathological conditions and other situations, and more than one may be experienced simultaneously or in succession. However, the three qualities vary in terms of their unpleasantness, with air hunger reported to be the most unpleasant. We emphasise the important interplay among various primary stimuli to breathlessness and other physiological and pathophysiological conditions, as well as animal management practices. For example, asphyxia/drowning of healthy mammals or killing those with respiratory disease using gases containing high carbon dioxide tensions is likely to lead to severe air hunger, while brachycephalic obstructive airway syndrome in modern dog and cat breeds increases respiratory effort at rest and likely leads to air hunger during exertion. Using this information as a guide, we encourage animal welfare scientists, veterinarians, laboratory scientists, regulatory bodies and others involved in evaluations of animal welfare to consider whether or not breathlessness contributes to any compromise they may observe or wish to avoid or mitigate."

Brachycephalic obstructive airway syndrome: a growing problem. Terry Emmerson. J. Small Animal Practice. November 2014;55(11):543-544. Quote: "The Cavalier King Charles spaniel (CKCS) is often considered a brachycephalic breed and can present with typical brachycephalic airway signs such as respiratory noise, snoring, stertor and exercise intolerance. They are represented in reviews of dogs undergoing corrective airway surgery for BOAS and dogs requiring tracheostomies (Torrez & Hunt 2006). However these dogs often do not demonstrate the typical abnormalities of the brachycephalic breeds. They often do not have an overlong palate as judged by standard criteria or stenotic nares or everted laryngeal ventricles. Some present with isolated laryngeal collapse and we have seen some dogs with concurrent laryngeal paralysis. As a breed they often have a particularly thick soft palate and small nasopharynx which may be the main factors driving the signs in this breed. Other breeds that can present with BOAS-like symptoms but often without the typical abnormalities include the bull terrier and Mastiff breeds. Like the CKCS, these breeds often do not have a surgically correctable problem. BOAS is a complex problem which currently we do not fully understand. We need to better understand the anatomical and breed variations in these cases and their relationship to severity of signs and postsurgical outcome. Current surgical options offer a way to alleviate signs and can provide significant improvement. However, there is still a frustrating subset of cases with poor outcomes that we struggle to identify pre-operatively. Surgery should be performed on affected dogs to improve quality of life and as a welfare issue. However, ultimately, the only way to truly improve this condition is by education of the public and breeders regarding the problems of these breeds and with breeding aimed at improving conformation."

Use of silicone tracheal stoma stents for temporary tracheostomy in dogs with upper airway obstruction. T. Trinterud, P. Nelissen, R. A. S. White. J. Small Animal Practice. November 2014;55(11):551-559. Quote: "Objectives: To report the use of silicone tracheal stoma stents for temporary tracheostomy in dogs with upper airway obstruction. Methods: Retrospective review of medical records for dogs in which silicone tracheal stoma stents were placed. Results: Eighteen dogs [including three cavalier King Charles spaniels] had a silicone tracheal stoma stent placed for maintenance of a tracheostomy stoma for periods ranging from three hours to eight months. No intra-operative or immediate postoperative complications were recorded. In 11 dogs the stent was removed by simple traction after a period ranging from 36 hours to 6 weeks, and the tracheal stoma was left to heal by second intention. Five of the 18 dogs were determined as being tracheostomy dependent and underwent conversion to permanent tracheostomy after a period ranging from five days to eight months following stent placement. One dog was euthanased after three months, with the stent still in place, because of poor respiratory function, and one dog [a CKCS] died of unrelated reasons ["severe immune-mediated thrombocytopenia (ITP)"]. In 6 of 10 dogs (60%) where the stent was in place for five days or more, granulation tissue formation caused dislodgement of the stent. Clinical Significance: Silicone tracheal stoma stents may be used as an alternative to conventional trache-ostomy tubes in selected dogs with upper airway obstruction. Long-term use of the stent beyond five days is not recommended because of granulation tissue formation. The long-term consequences of partial tracheal ring resection are unknown."

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2015

Introducing breathlessness as a significant animal welfare issue. NJ Beausoleila, DJ Mellora. N. Z. Vet. J. January 2015;63(1):44-51. Quote: Breathlessness is a negative affective experience relating to respiration, the animal welfare significance of which has largely been underestimated in the veterinary and animal welfare sciences. In this review, we draw attention to the negative impact that breathlessness can have on the welfare of individual animals and to the wide range of situations in which mammals may experience breathlessness. At least three qualitatively distinct sensations of breathlessness are recognised in human medicine--respiratory effort, air hunger and chest tightness--and each of these reflects comparison by cerebral cortical processing of some combination of heightened ventilatory drive and/or impaired respiratory function. Each one occurs in a variety of pathological conditions and other situations, and more than one may be experienced simultaneously or in succession. However, the three qualities vary in terms of their unpleasantness, with air hunger reported to be the most unpleasant. We emphasise the important interplay among various primary stimuli to breathlessness and other physiological and pathophysiological conditions, as well as animal management practices. For example, asphyxia/drowning of healthy mammals or killing those with respiratory disease using gases containing high carbon dioxide tensions is likely to lead to severe air hunger, while brachycephalic obstructive airway syndrome in modern dog and cat breeds increases respiratory effort at rest and likely leads to air hunger during exertion. Using this information as a guide, we encourage animal welfare scientists, veterinarians, laboratory scientists, regulatory bodies and others involved in evaluations of animal welfare to consider whether or not breathlessness contributes to any compromise they may observe or wish to avoid or mitigate.

Comparison of the Relationship between Cerebral White Matter and Grey Matter in Normal Dogs and Dogs with Lateral Ventricular Enlargement. Martin J. Schmidt, Steffi Laubner, Malgorzata Kolecka, Klaus Failing, Andreas Moritz,  Martin Kramer, Nele Ondreka. PLoS ONE 10(5): e0124174. May 2015. Quote: "Large cerebral ventricles are a frequent finding in brains of dogs with brachycephalic skull conformation, in comparison with mesaticephalic dogs. It remains unclear whether oversized ventricles represent a normal variant or a pathological condition in brachycephalic dogs. There is a distinct relationship between white matter and grey matter in the cerebrum of all eutherian mammals. The aim of this study was to determine if this physiological proportion between white matter and grey matter of the forebrain still exists in brachycephalic dogs with oversized ventricles. The relative cerebral grey matter, white matter and cerebrospinal fluid volume in dogs were determined based on magnetic-resonance-imaging datasets using graphical software. In an analysis of covariance (ANCOVA) using body mass as the covariate, the adjusted means of the brain tissue volumes of two groups of dogs were compared. Group 1 included 37 mesaticephalic dogs of different sizes with no apparent changes in brain morphology, and subjectively normal ventricle size. Group 2 included 35 brachycephalic dogs [including 7 cavalier King Charles spaniels, 4 of which were diagnosed with syringomyelia] in which subjectively enlarged cerebral ventricles were noted as an incidental finding in their magnetic-resonance-imaging examination. Whereas no significant different adjusted means of the grey matter could be determined, the group of brachycephalic dogs had significantly larger adjusted means of lateral cerebral ventricles and significantly less adjusted means of relative white matter volume. This indicates that brachycephalic dogs with subjective ventriculomegaly have less white matter, as expected based on their body weight and cerebral volume. Our study suggests that ventriculomegaly in brachycephalic dogs is not a normal variant of ventricular volume. Based on the changes in the relative proportion of WM and CSF volume, and the unchanged GM proportions in dogs with ventriculomegaly, we rather suggest that distension of the lateral ventricles might be the underlying cause of pressure related periventricular loss of white matter tissue, as occurs in internal hydrocephalus. ... The influence of ventriculomegaly on brain function in dogs is unclear. Detailed behavioural studies of the impact of WM loss on the full functional integration of the nervous system are necessary to clarify whether ventriculomegaly might be an indication for CSF shunting procedures in dogs."

Impact of Facial Conformation on Canine Health: Corneal Ulceration. Rowena M. A. Packer, Anke Hendricks, Charlotte C. Burn. PlosOne. May 2015. Quote: "Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. ... Several brachycephalic breeds have been identified as being predisposed to dry eye, including the Bulldog, Lhasa Apso, Shih Tzu, Pug, Pekingese, Boston Terrier and Cavalier King Charles Spaniel. Even moderately lowered tear production associated with dry eye may produce clinical signs in brachycephalic dogs, as a larger portion of the globe is exposed. In a UK based study, a higher proportion of brachycephalic dogs that were affected by ulcers, than were non-brachycephalic dogs with dry eye, e.g. 36% of Shih Tzus and 30% of Cavalier King Charles Spaniels versus 17% of dogs in the overall study population.  ... This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled) skull shape, the presence of a nasal fold (wrinkle), and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not), or if a previous diagnosis of corneal ulcer(s) was documented in the dogs’ histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%), small breed dogs (mean± SE weight: 11.4±1.1 kg), the most common being the Pug (n = 12 affected), the Shih Tzu (n = 4), the Bulldog and the Cavalier King Charles Spaniel (n = 3). ... Morphometric data were collected for each dog using previously defined measuring protocols, measuring 11 conformational features that were demonstrated to be breed-defining: muzzle length, cranial length, head width, eye width, neck length, neck girth, chest girth, chest width, body length, height at the withers and height at the base of tail (all in cm). ... A further morphometric predictor of interest for corneal ulcers was craniofacial ratio, (CFR): the muzzle length divided by the cranial length, which quantifies the degree of brachycephaly, was used to differentiate skull morphologies. [Photos at right: "This Cavalier King Charles Spaniel has a craniofacial ratio of 0.27 (muzzle length 28mm / cranial length 102mm), and a relative palpebral fissure width value of 33.3% ((palpebral fissure width 34mm / cranial length 102mm) *100"]  ... [B]rachycephalic dogs (craniofacial ratio <0.5) were twenty times more likely to be affected than non-brachycephalic dogs. A 10% increase in relative eyelid aperture width more than tripled the ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare."

Signalment, Clinical Presentation, Concurrent Diseases, and Diagnostic Findings in 28 Dogs with Dynamic Pharyngeal Collapse (2008–2013). J. A. Rubin, D.E. Holt, J. A. Reetz, D. L. Clarke. J. Vet. Intern. Med. May 2015; doi: 10.1111/jvim.12598. Quote: Background: Most information about pharyngeal collapse in dogs is anecdotal and extrapolated from human medicine. Asingle case report describing dynamic pharyngeal collapse in a cat has been published, but there is no literature describingthis disease process in dogs.Objective: To describe the signalment, clinical presentation, concurrent disease processes, and imaging findings of a population.of client-owned dogs with pharyngeal collapse.Animals: Twenty-eight client-owned dogs with pharyngeal collapse.Methods: Radiology reports of dogs for which fluoroscopy of the respiratory system was performed were reviewed retrospectively.Patients with a fluoroscopic diagnosis of pharyngeal collapse were included in the study population. Data regardingclinical signs, diagnostic, and pathologic findings were evaluated.Results: Twenty-eight dogs met the inclusion criteria. The median age of affected patients was 6.6 years, whereas medianbody condition score was 7/9. The most common clinical signs were coughing (n = 20) and stertor (n = 5). In 27 of 28 cases,a concurrent or previously diagnosed cardiopulmonary disorder was detected. The most common concurrent disease processeswere mainstem bronchi collapse (n = 18), tracheal collapse (n = 17), and brachycephalic airway syndrome (n = 8).Fluoroscopy identified complete pharyngeal collapse in 20 of 28 dogs.Conclusions: Pharyngeal collapse is a complex disease process that likely is secondary to long-term negative pressure gradientsand anatomic and functional abnormalities. Based on the findings of this study, pharyngeal fluoroscopy may be usefuldiagnostic test in patients with suspected tracheal and mainstem bronchial collapse to identify concurrent pharyngeal collapse.

Can we breathe easy about Brachycephalic Obstructive Airway Syndrome? Effects of severity on canine play, exercise and feeding behaviour. Monica Anghaei, Charlotte C. Brun. Conference: Canine Behaviour & Genetics. June 2015. Quote: "Brachycephalic Obstructive Airway Syndrome (BOAS) forms a continuum from mild to severe. It is most common in dogs with brachycephalic conformations and as such, this genetic predisposition exposes dogs to a series of respiratory complications. BOAS impairs canine quality of life when severe, but little is known about its effects on key positive aspects of behaviour when less severe. It is hypothesised that beyond certain severities, BOAS will: i. reduce ability to exercise and haemoglobin oxygenation following walking, ii. reduce playfulness, and iii. reduce appetite and increase difficulty eating. Quantitative behavioural observations were conducted on 47 brachycephalic dogs. Behaviour during (i) a 6-minute walk test, (ii) a play test (iii) and an appetite test was recorded. BOAS severity was measured using a previously validated Owner Reported Breathing (ORB) score: 0 = unaffected; 40 = maximum severity. Increasing BOAS severity tended (non-significantly) to decrease oxygenation after exercise [at right, a CKCS is being measured with a  pulse a oximeter after exercise], increased time to ingest per food pellet , and decrease in energetic play behaviours e.g. Play Bow; and increase breathing noises in all three domains. An owner questionnaire conducted on 2265 brachycephalic dogs [including cavalier King Charles spaniels] indicated the severity scores for mild BOAS are 8-15, moderate BOAS are 16-26 and severe are 27-40 ORB score, with owner-perceived canine welfare significantly declining as severity increased. Mild BOAS has less effect on canine welfare than sometimes assumed. However, moderate BOAS affects at least two of the welfare domains tested and severe BOAS is recognised to negatively impacts all exercise, appetite and play domains. This information would will help make recommendations for owners, breeders and veterinarians on appropriate treatment to maximise welfare in affected dogs.

Epidemiological associations between brachycephaly and upper respiratory tract disorders in dogs attending veterinary practices in England. Dan G. O’Neill, Caitlin Jackson, Jonathan H. Guy, David B. Church, Paul D. McGreevy, Peter C. Thomson, Dave C. Brodbelt. Canine Genetics & Epidemiology. July 2015;2:10. Quote: "Background: Brachycephalic dog breeds are increasingly common. Canine brachycephaly has been associated with upper respiratory tract (URT) disorders but reliable prevalence data remain lacking. Using primary-care veterinary clinical data, this study aimed to report the prevalence and breed-type risk factors for URT disorders in dogs. Results: The sampling frame included 170,812 dogs attending 96 primary-care veterinary clinics participating within the VetCompass Programme. Two hundred dogs were randomly selected from each of three extreme brachycephalic breed types (Bulldog, French Bulldog and Pug) and three common small-to medium sized breed types (moderate brachycephalic: Yorkshire Terrier and non-brachycephalic: Border Terrier and West Highland White Terrier). Information on all URT disorders recorded was extracted from individual patient records. Disorder prevalence was compared between groups using the chi-squared test or Fisher’s test, as appropriate. During the study, 83 (6.9 %) study dogs died. Extreme brachycephalic dogs (median longevity: 8.6 years, IQR: 2.4-10.8) were significantly younger at death than the moderate and non-brachycephalic group of dogs (median 12.7 years, IQR 11.1-15.0) (P < 0.001). A higher proportion of deaths in extreme brachycephalic breed types were associated with URT disorders (4/24 deaths, 16.7 %) compared with the moderate and non-brachycephalic group (0/59 deaths, 0.0 %) (P = 0.001). The prevalence of having at least one URT disorder in the extreme brachycephalic group was higher (22.0 %, 95 % confidence interval (CI): 18.0-26.0) than in the moderate and non-brachycephalic group (9.7 %, 95 % CI: 7.1-12.3, P < 0.001). The prevalence of URT disorders varied significantly by breed type: Bulldogs 19.5 %, French Bulldogs 20.0 %, Pugs 26.5 %, Border Terriers 9.0 %, West Highland White Terriers 7.0 % and Yorkshire Terriers 13.0 % (P < 0.001). After accounting for the effects of age, bodyweight, sex, neutering and insurance, extreme brachycephalic dogs had 3.5 times (95 % CI: 2.4-5.0, P < 0.001) the odds of at least one URT disorder compared with the moderate and non-brachycephalic group. Conclusions: In summary, this study reports that URT disorders are commonly diagnosed in Bulldog, French Bulldog, Pug, Border Terrier, WHWT and Yorkshire Terrier dogs attending primary-care veterinary practices in England. The three extreme brachycephalic breed types (Bulldog, French Bulldog and Pug) were relatively short-lived and predisposed to URT disorders compared with three other small-to-medium size breed types that are commonly owned (moderate brachycephalic Yorkshire Terrier and non-brachycephalic: Border Terrier and WHWT)."

Brachycephalic Airway Syndrome: Tips for Successful Diagnosis and Surgery. Katrin Saile. DVM360. September 2015. Quote: "Brachycephalic syndrome refers to a combination of abnormalities in the nose, mouth and trachea of certain breeds of dogs that can cause significant respiratory abnormalities. ... Brachycephalic dogs and cats have early ankylosis in the cartilages at the base of their skull, leading to a shortened longitudinal skull axis. The most common breeds affected by brachycephalic syndrome include English bulldogs, French bulldogs, Pugs, and Boston terriers. Cavalier King Charles spaniels, Shih-Tzus, and Pekinese are also over-represented. ... Most commonly, patients present with stenotic nares, an elongated soft palate, and everted laryngeal saccules. Several components of brachycephalic syndrome can be surgically corrected and dogs can have a good prognosis if the disease is not too advanced."

Clinical Features and Outcome of Dogs with Epiglottic Retroversion With or Without Surgical Treatment: 24 Cases. S.C. Skerrett, J.K. McClaran, P.R. Fox, D. Palma. J. Vet. Int. Med. October 2015. Quote: "Background: Published information describing the clinical features and outcome for dogs with epiglottic retroversion (ER) is limited. Hypothesis/Objectives: To describe clinical features, comorbidities, outcome of surgical versus medical treatment and long-term follow-up for dogs with ER. We hypothesized that dogs with ER would have upper airway comorbidities and that surgical management (epiglottopexy or subtotal epiglottectomy) would improve long-term outcome compared to medical management alone. Animals: Twenty-four client-owned dogs [one cavalier King Charles spaniel]. Methods: Retrospective review of medical records to identify dogs with ER that underwent surgical or medical management of ER. Results: Dogs with ER commonly were middle-aged to older, small breed, spayed females with body condition score (BCS) ≥6/9. Stridor and dyspnea were the most common presenting signs. Concurrent or historical upper airway disorders were documented in 79.1% of cases. At last evaluation, 52.6% of dogs that underwent surgical management, and 60% of dogs that received medical management alone, had decreased severity of presenting clinical signs. In dogs that underwent surgical management for ER, the incidence of respiratory crisis decreased from 62.5% before surgery to 25% after surgical treatment. The overall calculated Kaplan–Meier median survival time was 875 days. Conclusion and clinical importance: Our study indicated that a long-term survival of at least 2 years can be expected in dogs diagnosed with epiglottic retroversion. The necessity of surgical management cannot be determined based on this data, but dogs with no concurrent upper airway disorders may benefit from a permanent epiglottopexy to alleviate negative inspiratory pressures."

Impact of Facial Conformation on Canine Health: Brachycephalic Obstructive Airway Syndrome. Rowena M. A. Packer, Anke Hendricks, Michael S. Tivers, Charlotte C. Burn. PlosOne. October 2015. Quote: "The domestic dog may be the most morphologically diverse terrestrial mammalian species known to man; pedigree dogs are artificially selected for extreme aesthetics dictated by formal Breed Standards, and breed-related disorders linked to conformation are ubiquitous and diverse. Brachycephaly–foreshortening of the facial skeleton–is a discrete mutation that has been selected for in many popular dog breeds e.g. the Bulldog, Pug, and French Bulldog. A chronic, debilitating respiratory syndrome, whereby soft tissue blocks the airways, predominantly affects dogs with this conformation, and thus is labelled Brachycephalic Obstructive Airway Syndrome (BOAS). Despite the name of the syndrome, scientific evidence quantitatively linking brachycephaly with BOAS is lacking, but it could aid efforts to select for healthier conformations. Here we show, in (1) an exploratory study of 700 dogs of diverse breeds and conformations [including 26 cavalier King Charles spaniels], and (2) a confirmatory study of 154 brachycephalic dogs [including 11 CKCSs], that BOAS risk increases sharply in a non-linear manner as relative muzzle length shortens. BOAS only occurred in dogs whose muzzles comprised less than half their cranial lengths. Thicker neck girths also increased BOAS risk in both populations: a risk factor for human sleep apnoea and not previously realised in dogs; and obesity was found to further increase BOAS risk. This study provides evidence that breeding for brachycephaly leads to an increased risk of BOAS in dogs, with risk increasing as the morphology becomes more exaggerated. As such, dog breeders and buyers should be aware of this risk when selecting dogs, and breeding organisations should actively discourage exaggeration of this high-risk conformation in breed standards and the show ring."

Clinical effects of the use of a bipolar vessel sealing device for soft palate resection and tonsillectomy in dogs, with histological assessment of resected tonsillar tissue. DA Cook, PA Moses, JT Mackie. Australian Vet. J. November 2015;93(12):445-451. Quote: "Objective: To investigate whether soft palate resection and tonsillectomy with a bipolar vessel sealing device (BVSD) improves clinical respiratory score. To document histopathological changes to tonsillar tissue following removal with a BVSD. Methods & Results: Case series of 22 dogs with clinical signs of upper respiratory obstruction related to brachycephalic airway syndrome. Soft palate and tonsils were removed using a BVSD. Alarplasty and saccullectomy were also performed if indicated. A clinical respiratory score was assigned preoperatively, 24-h postoperatively and 5 weeks postoperatively. Excised tonsillar samples were measured and then assessed histologically for depth of tissue damage deemed to be caused by the device. Depth of tissue damage was compared between two power settings of the device. Soft palate resection and tonsillectomy with a BVSD lead to a significant improvement in respiratory scores following surgery. Depth of tissue damage was significantly less for power setting 1 compared with power setting 2. Using power setting 1, median calculated depth of tonsillar tissue damage was 3.4 mm (range 1.2–8.0). One dog experienced major complications. Conclusion: Soft palate resection and tonsillectomy with a BVSD led to significant improvement in clinical respiratory score."

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2016

Histopathologic and immunohistochemical features of soft palate muscles and nerves in dogs with an elongated soft palate. Kiyotaka Arai, Masanori Kobayashi, Yasuji Harada, Yasushi Hara, Masaki Michishita, Kozo Ohkusu-Tsukada, Kimimasa Takahashi. Amer. J. Vet. Research. January 2016;77(1):77-83. Quote: "Objective: To histologically evaluate and compare features of myofibers within the elongated soft palate (ESP) of brachycephalic and mesocephalic dogs with those in the soft palate of healthy dogs and to assess whether denervation or muscular dystrophy is associated with soft palate elongation. Sample: Soft palate specimens from 24 dogs with ESPs (obtained during surgical intervention) and from 14 healthy Beagles (control group). ... The brachycephalic breeds included French Bulldog (n = 6), Pug (5), Pomeranian (3), Shih Tzu (2), Cavalier King Charles Spaniel (2), Pekinese (1), and Bulldog (1). ... Procedures: All the soft palate specimens underwent histologic examination to assess myofiber atrophy, hypertrophy, hyalinization, and regeneration. The degrees of atrophy and hypertrophy were quantified on the basis of the coefficient of variation and the number of myofibers with hyalinization and regeneration. The specimens also underwent immunohistochemical analysis with anti-neurofilament or anti-dystrophin antibody to confirm the distribution of peripheral nerve branches innervating the palatine myofibers and myofiber dystrophin expression, respectively. Results: Myofiber atrophy, hypertrophy, hyalinization, and regeneration were identified in almost all the ESP specimens. Degrees of atrophy and hypertrophy were significantly greater in the ESP specimens, compared with the control specimens. There were fewer palatine peripheral nerve branches in the ESP specimens than in the control specimens. Almost all the myofibers in the ESP and control specimens were dystrophin positive. Conclusions and Clinical Relevance: These results suggested that palatine myopathy in dogs may be caused, at least in part, by denervation of the palatine muscles and not by Duchenne- or Becker-type muscular dystrophy. These soft palate changes may contribute to upper airway collapse and the progression of brachycephalic airway obstructive syndrome."

Canine tracheal collapse. S. W. Tappin. J. Sm. Anim. Pract. January 2016;57(1):9-17. Quote: "Tracheal collapse occurs most commonly in middle-aged, small breed dogs. Clinical signs are usually proportional to the degree of collapse, ranging from mild airway irritation and paroxysmal coughing to respiratory distress and dyspnoea. Diagnosis is made by documenting dynamic airway collapse with radiographs, bronchoscopy or fluoroscopy. Most dogs respond well to medical management and treatment of any concurrent comorbidities. Surgical intervention may need to be considered in dogs that do not respond or have respiratory compromise. A variety of surgical techniques have been reported although extraluminal ring prostheses or intraluminal stenting are the most commonly used. Both techniques have numerous potential complications and require specialised training and experience but are associated with good short- and long-term outcomes."

Comparison between computed tomographic characteristics of the middle ear in nonbrachycephalic and brachycephalic dogs with obstructive airway syndrome. Raquel Salgüero, Michael Herrtage, Mark Holmes, Paddy Mannion, Jane Ladlow. Vet. Radiology & Ultrasound. March 2016;57(2):137-143. Quote: “Prevalence of subclinical middle ear lesions in dogs that undergo computed tomography (CT) and magnetic resonance imaging of the head has been reported up to 41%. ... Eustachian tube dysfunction has been postulated to be the cause of the high prevalence (54%) of middle ear effusions in Cavalier King Charles spaniels. ... A predisposition in brachycephalics has been suggested, however evidence-based studies are lacking. Aims of this retrospective cross-sectional study were to compare CT characteristics of the middle ear in groups of nonbrachycephalic and brachycephalic dogs that underwent CT of the head for conditions unrelated to ear disease, and test associations between thickness of the soft palate and presence of subclinical middle ear lesions. One observer recorded CT findings for each dog without knowledge of group status. A total of 65 dogs met inclusion criteria (25 brachycephalic, 40 nonbrachycephalic). Brachycephalic dogs had a significantly thicker bulla wall (P = 2.38 × 10−26) and smaller luminal volume (P = 5.74 × 10−20), when compared to nonbrachycephalic dogs. Soft palate thickness was significantly greater in the brachycephalic group (P = 2.76 × 10−9). Nine of 25 brachy-cephalic dogs had material in the lumen of the tympanic cavity, compared to zero of 45 of non-brachycephalics. Within the brachycephalic group, a significant difference in mean soft palate thickness was identified for dogs with material in the middle ear (12.2 mm) vs. air-filled bullae (9 mm; P = 0.016). Findings from the current study supported previous theories that brachycephalic dogs have a greater prevalence of subclinical middle ear effusion and smaller bulla luminal size than nonbrachycephalic dogs. ... When the Eustachian tube function is impaired, middle ear pressure becomes more negative, drawing extracellular fluid into the bulla and producing serous effusion. 12 Similar changes were found in Cavalier King Charles spaniels, where a greater thickness of the soft palate and reduced nasopharyngeal aperture were significantly associated with subclinical otitis media ... Authors recommend that the bulla lumen volume formula previously developed for mesaticephalic dogs, (−0.612 + 0.757 [lnBW]) be adjusted to 1/3(−0.612 + 0.757 [lnBW]) for brachycephalic breeds. ... Further prospective studies are needed with a larger number of brachycephalic dogs and to compare our breeds with Cavalier King Charles spaniels as previous publications have already shown the presence of subclinical otitis media in this breed.”

How does multilevel upper airway surgery influence the lives of dogs with severe brachycephaly? Results of a structured pre- and postoperative questionnaire administered to dog owners. S. Pohla, F. Roedlera, G.U. Oechtering. Vet. J. February 2016. Quote: "Using a structured questionnaire, the present study investigated the dog owner-perceived severity and frequency of a broad spectrum of welfare-relevant impairments 2 weeks before and 6 months after brachycephalic dogs underwent a recently developed multi-level upper airway surgery. All dogs underwent surgical treatment of stenotic nares (ala-vestibuloplasty), the nasal cavity (laser-assisted turbinectomy, LATE), the pharynx (palatoplasty and tonsillotomy), and if indicated, laryngeal surgery (laser-assisted ablation of everted ventricles and partial cuneiformectomy). Questionnaire data from owners of 37 Pugs and 25 French bulldogs were evaluated. In all dogs, the clinical signs associated with brachycephaly improved markedly after surgery. Most encouraging was the striking reduction in life-threatening events by 90% (choking fits decreased from 60% to 5% and collapse from 27% to 3%). The incidence of sleeping problems decreased from 55% to 3%, and the occurrence of breathing sounds declined by approximately 50%. There was a marked improvement in exercise tolerance and a modest improvement in heat tolerance. Dogs with severe brachycephaly benefitted substantially from multi-level surgery, and there were particular improvements in the incidences of severe impairment and life-threatening events. However, despite the marked improvement perceived by dog owners, these dogs remained clinically affected and continued to show welfare-relevant impairments caused by these hereditary disorders.

Brachycephalic Syndrome. Gilles Dupré, Dorothee Heidenreich. Vet. Clinics of No. America: Sm. Anim. Pract. March 2016. Quote: "Brachycephalic syndrome (BS) is an established cause of respiratory distress in brachycephalic breeds. Breeds most commonly affected are English and French bulldogs, pugs, and Boston terriers; however, Pekingese, Shih tzu, Cavalier King Charles Spaniels, Boxers, Dogue de Bordeaux, and Bullmastiffs are also categorized as brachycephalic dogs. Most owners report heat, stress and exercise intolerance, snoring, inspiratory dyspnea, and in severe cases, cyanosis and even syncopal episodes. Sleep apneas can be observed,5 and occasionally gastrointestinal signs such as vomiting and regurgitation. KEY POINTS: Skull conformation anomalies in brachycephalic breeds lead to compression of nasal passages. Additional mucosal hyperplasia and secondary collapse of the upper airway contribute to a multilevel obstruction and the genesis of the so-called brachycephalic syndrome. Surgical treatments usually include widening of stenotic nares as well as various palatoplasty techniques to improve airflow through the rima glottidis. The overall prognosis for a significant improvement is excellent."

Efficacy of bronchial stenting in dogs with myxomatous mitral valve disease and bronchial collapse. Dar Ozer, Samantha Siess, Brienne Williams, Nikki Gaudette, George Kramer. J. Vet. Int. Med. June 2016. 2016 ACVIM Forum Abstract C-03. Quote: Chronic airway disease and myxomatous mitral valve disease (MMVD) are frequent comorbidities in small breed dogs. Bronchial collapse can cause coughing, tachypnea and hypoxemia. Pulmonary hypertension can be seen with both MMVD and chronic airway disease. The purpose of this study was to review outcomes in dogs that had bronchial stents placed due to bronchial collapse. It was hypothesized that moderate to severe MMVD or the presence of pulmonary hypertension would not have a negative effect on lifespan after stent placement. Medical records of 18 small breed dogs that had bronchial stent placement for chronic coughing secondary to bronchial collapse were reviewed. A hierarchical multiple linear regression analysis was conducted to predict lifespan after bronchial stent placement based on age at time of stent placement, severity of MMVD and the presence of pulmonary hypertension. Eighteen dogs had bronchial stents placed over a period of 7 years. Age at the time of stent placement ranged from 6.5 years to 14 years of age (M = 10.47 1.85). Breeds represented included Cavalier King Charles spaniel (2), beagle (2), Chihuahua (4), Pomeranian (3), toy poodle (2), Yorkshire terrier (2), Maltese (1), Coton de Tulear (1) and shih tzu (1). There were 11 males and 7 females. Twelve dogs (66.67%) had evidence of moderate to severe MMVD and 4 (22.22%) had evidence of pulmonary hypertension. Six dogs (33.33%) had CHF prior to stent placement and 6 dogs (33.33%) had CHF after stent placement. Syncope was reported in 6 dogs prior to stent placement and 5 dogs after stent placement. The average lifespan after stent placement was 203.56 250.72 days. Three dogs are currently alive post-stent placement (1013, 559 and 411 days). A hierarchical multiple linear regression was calculated to predict lifespan after placement of a bronchial stent based on age at the time of stent placement, the presence of pulmonary hypertension, and severity of MMVD. In stage one, age at the time of stent placement significantly predicted lifespan after placement of a bronchial stent (b = 7.10, P < .02); with lifespan decreasing by 7.10 days for each additional month of age at the time of stent placement. The presence of pulmonary hypertension did not significantly predict lifespan (b = 235.32, P = .10). Severity of MMVD did not contribute significantly to the model in stage two (b = 101.38, P = 0.43). Results from this study indicate that the severity of MMVD or the presence of pulmonary hypertension did not negatively affect lifespan after bronchial stent placement. As such, moderate to severe MMVD and the presence of pulmonary hypertension should not be viewed as exclusion criteria when assessing candidates for possible bronchial stenting. Prospective studies should be conducted to further investigate the clinical benefit of bronchial stenting in dogs with severe bronchial collapse.

Brachycephalic Syndrome. Comparison Between Conventional Surgical Techniques, Resection with Surgical Laser and Plasty. Advantages and Disadvantages of Each. Gala Secanella Garcés. Univ. Barcelona. June 2016. Quote: Dog breeds most commonly affected are English and French bulldogs, Pugs, Boston terriers, Pekingese, Shih tzu, Maltese, Cavalier King Charles Spaniels, Boxers, Yorkshire terriers, Pinschers miniature, Dogue de Bordeaux and Bullmastiffs. ... The definitive treatment for the BS [brachycephalic syndrome] is always surgical. Early intervention can slow down the progression of the signs and complications. There are several surgical techniques and, during the last years, the use of CO2 laser ensures less surgical time, bleeding, swelling and intra and postoperative pain, as well as a more precise tissue ressection. A possible explanation for the poor therapeutic success after conventional surgeries, could be the lack of consideration in the diagnosis, management and treatment of the rest of intranasal structures. To understand the BS, all the efforts should relapse into the selection of these breeds, so that in the future, the objective is to encourage more moderate craniofacial morphologies in order to reduce the prevalence and severity of BS.

Use of CT to evaluate and compare intranasal features in brachycephalic and normocephalic dogs. M. Auger, K. Alexander, G. Beauchamp, M. Dunn. J. Small Animal Pract. October 2016;57(10):529-536. Quote: Objectives: To evaluate and compare nasal mucosal contact, septal deviation and caudal aberrant nasal turbinates in brachycephalic and normocephalic dogs using computed tomography. Methods: Dogs without nasal disease and having undergone computed tomography scan of the head (plica alaris to the cribiform plate) were retrospectively selected and divided into brachycephalic and normocephalic groups. Eighteen brachycephalic [including two cavalier King Charles spaniels] and 32 normocephalic dogs were included. Anatomic criteria were used to locate predetermined pairs of intranasal structures and nasal mucosal contact was described as present or absent for each site. Septal deviations were identified and measured using angle of septal deviation. Caudal aberrant nasal turbinates were identified and categorised when present.  [View at right shows contact between the concha nasalis ventralis and the nasal septum in a 7.3 year old CKCS.] Results: Prevalence of nasal mucosal contact was significantly higher in brachycephalic dogs. No significant difference was seen in prevalence or in angle of septal deviation between groups. Prevalence of caudal aberrant nasal turbinates was significantly higher in brachycephalic dogs. Clinical Significance: Nasal mucosal contact and caudal aberrant nasal turbinates were significantly more prevalent in brachycephalic dogs than in normocephalic dogs in our study. Computed tomography can be a valuable aid in obtaining data on nasal mucosal contact, caudal aberrant nasal turbinates and septal deviations. Combination of computed tomography with endoscopy and functional airway testing would be useful to further evaluate the correlation between intranasal features and symptoms of brachycephalic airway syndrome.

Perfusion-weighted Magnetic Resonance Imaging of Brachycephalic Dogs with Ventriculomegaly. M. J. Schmidt, A. Hartmann, K. H. von Pückler, L. Hähnsen, N. Ondreka. Vet. Rad. & Ultra. October 2016;57(6):646-669. Quote: Introduction: It has been shown that ventriculomegaly in dogs is associated with a loss of periventricular white matter comparable to clinical relevant internal hydrocephalus or normal pressure hydrocephalus (NPH). The pathophysiology of ventricular distension is unclear currently. The aim of this study was to compare brain perfusion in dogs with and without ventriculomegaly using perfusion-weighted magnetic resonance imaging to clarify, as to whether abnormal perfusion might be involved in the pathophysiology of ventriculomegaly. Materials and methods: Perfusion was measured in 23 Cavalier King Charles spaniels with ventriculomegaly, 10 healthy Beagle dogs were examined as a control group. Perfusion-weighted images were acquired using a dynamic multishot fast-field echo-EPI in a dorsal plane. Forty acquisitions per slice were acquired. Contrast was automatically injected using an automatic pump (0.2 mmol/kg body weight) in 20 ml crystalloid solution with an injection rate of 5 ml/s. Contrast was given at the 10th acquisition. Perfusion was measured using free-hand regions of interest (ROI) in five brain regions: periventricular white matter, caudate nucleus, parietal cortex, hippocampus, and thalamus using the STROKETOOL software tool. Time to peak (TTP), regional cerebral blood flow (rCBF), regional blood volume (rCBV), and mean transit time (MTT) was measured. Intraobserver variability was measured using kappa statistics. Differences between groups were tested using Mann–Whitney U-tests. Significance level was <0.05. Results: rCBF and rCBV were significantly lower in the periventricular white matter of the dogs with ventriculomegaly compared to control dogs (P < 0.001) but not for the other ROIs. Kappa statistics revealed substantial agreement between measurements (0.82). Discussion: Based on the differences in periventricular perfusion ventriculomegaly should be interpreted as a form of NPH as suggested previously. The impaired perfusion might be the reason for the reduced white matter volume in these dogs. This has been shown in laboratory rodents with experimentally induced hydrocephalus and humans with NPH. Cognitive studies should be conducted to investigate a possible impairment of memory, learning, and spatial orientation as present in humans with NPH.

Developmental and Evolutionary Significance of the Zygomatic Bone. Yann Heuzé, Kazuhiko Kawasaki, Tobias Schwarz, Jeffrey J. Schoenebeck, Joan T. Richtsmeier. Anat. Rec. December 2016;299(12):1616-1630. Quote: The zygomatic bone is derived evolutionarily from the orbital series. In most modern mammals the zygomatic bone forms a large part of the face and usually serves as a bridge that connects the facial skeleton to the neurocranium. Our aim is to provide information on the contribution of the zygomatic bone to variation in midfacial protrusion using three samples; humans, domesticated dogs, and monkeys. In each case, variation in midface protrusion is a heritable trait produced by one of three classes of transmission: localized dysmorphology associated with single gene dysfunction, selective breeding, or long-term evolution from a common ancestor. We hypothesize that the shape of the zygomatic bone reflects its role in stabilizing the connection between facial skeleton and neurocranium and consequently, changes in facial protrusion are more strongly reflected by the maxilla and premaxilla. Our geometric morphometric analyses support our hypothesis suggesting that the shape of the zygomatic bone has less to do with facial protrusion. By morphometrically dissecting the zygomatic bone we have determined a degree of modularity among parts of the midfacial skeleton suggesting that these components have the ability to vary independently and thus can evolve differentially. From these purely morphometric data, we propose that the neural crest cells that are fated to contribute to the zygomatic bone experience developmental cues that distinguish them from the maxilla and premaxilla. The spatiotemporal and molecular identity of the cues that impart zygoma progenitors with their identity remains an open question that will require alternative data sets. ... When the shape of the left canine facial skeleton is analyzed using PCA [principal components analysis], the first PC accounts for 79% of the total shape variation for which size (CS) explains 57% (P < 0.0001). Shape variation of the canine facial skeleton separates canine individuals primarily along PC1 (Fig. 6a) according to the relative magnitude of facial retrusion with the pug and bulldog, and to a lesser degree Lhasa apso, cavalier King Charles spaniel, and boxer tending towards the negative end of PC1 (retrognathic dogs), and the Scottish terrier, flat coated retriever and greyhound anchoring the positive end (prognathic dogs). ... Given the variation in size among dog breeds, we were interested in the relative size variation of the different anatomical units of the facial skeleton studied. To determine whether size varies in a pattern similar among the different anatomical units we studied (i.e., facial skeleton, premaxilla, and maxilla, zygoma), we used centroid size of the facial skeleton, premaxilla, maxilla, and zygoma as a proxy for size of each anatomical unit. The mean plot of these four anatomical units grouped by breed indicates that size varies according to a similar pattern among the different anatomical units forming the facial skeleton. The zygoma however appears a bit “out of phase” (larger than expected) relative to the pattern of centroid size estimated for the other facial units for the retrognathic breeds (boxer, bulldog, pug and Rottweiler) and the cavalier King Charles spaniel and cocker spaniel.

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2017

Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel. Susan P. Knowler, Chloe Cross, Sandra Griffiths, Angus K. McFadyen, Jelena Jovanovik, Anna Tauro, Zoha Kibar, Colin J. Driver, Roberto M. La Ragione, Clare Rusbridge. PLOS One. January 2017. Quote: Objectives: To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel [CKCS] using morphometric [the quantitative analysis of form, a concept that encompasses size and shape] measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods: This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and olfactory lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results: Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort [31 CKCS in the hindbrain study (HBS) and 16 CKCSs in the whole brain study (WBS)] had the most natural, wolf-like, skull conformation in terms of ellipticity. The CM pain cohort [28 CKCSs in HBS and 25 CKCSs in WBS] was characterised by increased brachycephaly with greatest rostral forebrain flattening, shortest basicranium and compensatory cranial height. However, in this cohort, an increased distance between the occiput and atlas provided fewer impediments to CSF dynamics at the foramen magnum and reduced the risk for SM. The SM cohort [71 CKCSs in HBS and 31 CKCSs in WBS] exhibited two conformation anomalies. One phenotype variation was influenced by incongruities at the craniocervical junction and increased proximity of the dens producing a ‘concertina’ type flexure with medullary elevation. The other phenotypic variation was influenced by increased brachycephaly resulted in a ‘concertina’ type flexure similar to the CM pain cohort. However, both SM variations were characterised by an apparent reduction in caudal fossa volume which compromised the CSF dynamics in the spinal cord. Conclusion: Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It might identify dogs at risk of SM and CM pain to improve diagnosis and make available a means for screening breeding dogs and provide estimated breeding values. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise the neural parenchyma and impede cerebrospinal fluid flow. (Motion picture highlights the dynamic changes of the skull conformation and brain parenchyma associated with progressive brachycephaly and airorhynchy, shortening of the basicranium and supraoccipital bones and the proximity and angulation of the atlas and dens.)

Time-dependent changes and prognostic value of lactatemia during the first 24 hours of life in brachycephalic newborn dogs. C. Castagnetti, M. Cunto, C. Bini, J. Mariella, S. Capolongo, D. Zam. Theriogenology. February 2017. Quote: Blood lactate concentration is known to be a good prognostic indicator associated with the severity of illness and the patient's outcome both in human and veterinary medicine. It also plays a significant role in the assessment of the newborn, being a good indicator of fetal hypoxia and the ideal predictor of morbidity at term in babies. In veterinary neonatal medicine, hyperlactatemia is considered a valid prognostic marker in critically ill foals; moreover, blood lactate measurement has been proposed for the evaluation of newborn viability and the assessment of fetal distress during delivery in dogs. Unfortunately, only a few studies have been published concerning the canine species. The present work examines 67 brachycephalic newborn dogs and their mothers, with the aim to evaluate the time-dependent changes of blood lactate and glucose concentration during the first 24 h after vaginal or caesarean delivery both in puppies and bitches. ... The study included seven pregnant bitches examined in the period 2012-2014. Six of them were English Bulldogs (four belonging to a breeding kennel and two private-owned) and one was a private-owned Cavalier King Charles Spaniel. ... To our knowledge, this is the first published study examining the time-dependent changes of these parameters in the bitch after parturition. Within the studied population of puppies, non-surviving was significantly associated with a higher lactatemia and a lower APGAR score. Blood lactate was high at birth then progressively decreased during the first 24 h of life and a lack of normalization of blood lactate levels within this time interval was suggestive for a poor prognosis for the newborn dogs; moreover, the decrease appeared to be slower after vaginal delivery. Lactatemia also showed a positive correlation with glycemia at birth. Concerning the bitches examined, blood lactate was found to be significantly higher after vaginal delivery than after caesarean section; the normalization occurred within 24 h after parturition. Blood glucose level was significantly higher at 2 h from delivery both in the group of bitches submitted to caesarean section and in those undergoing natural whelping but no statistical correlation was found between maternal glycemia and lactatemia. The results of the present study highlighted that the monitoring of lactatemia during the first 24 h of life, in association with the assessment of the APGAR score at birth, can be an useful prognostic tool helping to identify the most severely distressed puppies and to provide them an adequate support. Hghlights: • Lactate plays a significant role in the assessment of the newborn, both in human and veterinary medicine. • There are no published studies reporting the time-dependent changes of lactatemia during the first 24 h of life either in brachycephalic dogs or in other breeds. • The clearance of blood lactate is more rapid after caesarean section, since in this case puppies do not experience the stress of labour. • The time-dependent decrease of blood lactate concentration is missing or very slow in non-surviving puppies. • Monitoring of lactatemia during the first 24 h life, in association with the assessment of the APGAR score at birth, can be an useful prognostic tool helping to identify the most severely distressed puppies.

Anesthetic Protocols for Brachycephalic Dogs. Tasha McNerney. Vet. Team Brief. March 2017. Quote: Brachycephalic dogs are becoming more popular as pets, which means veterinary nurses are more likely to be asked to anesthetize these dogs in practice. Brachycephalic dogs have a relatively broad, short skull, usually with the breadth at least 80% of the length.2 They often have anatomic abnormalities (eg, stenotic nares, elongated soft palate, hypoplastic trachea, laryngeal collapse, everted laryngeal saccules), known as brachycephalic syndrome, which can cause upper airway obstruction and mandate the use of special protocols when administering anesthesia.

The Nationwide Brachycephalic Breed Disease Prevalence Study: Short-nosed breeds more often affected by common conditions, not just known issues. NationwideDVM.com March 2017.  Quote: The American Kennel Club lists three brachycephalic breeds (bulldogs, French bulldogs and boxers) in its top 10 most popular breeds; seven in the organization’s top 25. The AKC reports the French bulldog is the most popular breed in New York City, with bulldogs and Cavalier King Charles spaniels at No. 1 in select Manhattan ZIP codes. Nationwide’s proprietary claims data bears out the popularity of these breeds. Of the 1.27 million dogs whose health insurance claims were analyzed for this study [Figure 1], 15% were members of one of the 24 breeds identified as brachycephalic [including the CKCS]. (Nationwide’s list of all breeds includes more than 300 purebreds and crossbreds, not including five classifications of mixed breeds by size.) ... By examining the issues of brachycephalic dogs from a different angle—analyzing common conditions, not brachycephalic-specific ones—Nationwide has expanded the field of inquiry and set a foundation for further study. In so doing, the company is assisting veterinarians, pet owners, breed associations and other stakeholders in the common goal of working together to improve the health of these popular dogs. With an analysis that shows brachycephalic breeds significantly more impacted than their structurally normal counterparts across a range of common conditions, Nationwide has opened a new topic for discussion. In so doing, we hope to help improve the quality of life for these dogs, and to lessen the expense their owners have in caring for them.

Canine Brachycephaly Is Associated with a Retrotransposon-Mediated Missplicing of SMOC2. Thomas W. Marchant, Edward J. Johnson, Lynn McTeir, Craig I. Johnson, Adam Gow, Tiziana Liuti, Dana Kuehn, Karen Svenson, Mairead L. Bermingham, Michaela Drögemüller, Marc Nussbaumer, Megan G. Davey, David J. Argyle, Roger M. Powell, Sérgio Guilherme, Johann Lang, Gert Ter Haar, Tosso Leeb, Tobias Schwarz, Richard J. Mellanby, Dylan N. Clements, Jeffrey J. Schoenebeck. Current Biology. May 2017. Quote: In morphological terms, “form” is used to describe an object’s shape and size. In dogs, facial form is stunningly diverse. Facial retrusion, the proximodistal shortening of the snout and widening of the hard palate is common to brachycephalic dogs and is a welfare concern, as the incidence of respiratory distress and ocular trauma observed in this class of dogs is highly correlated with their skull form. Progress to identify the molecular underpinnings of facial retrusion is limited to association of a missense mutation in BMP3 among small brachycephalic dogs. Here, we used morphometrics of skull isosurfaces derived from 374 pedigree and mixed-breed dogs to dissect the genetics of skull form [including 6 cavalier King Charles spaniels]. Through deconvolution of facial forms, we identified quantitative trait loci that are responsible for canine facial shapes and sizes. Our novel insights include recognition that the FGF4 retrogene insertion, previously associated with appendicular chondrodysplasia, also reduces neurocranium size. Focusing on facial shape, we resolved a quantitative trait locus on canine chromosome 1 to a 188-kb critical interval that encompasses SMOC2. An intronic, transposable element within SMOC2 promotes the utilization of cryptic splice sites, causing its incorporation into transcripts, and drastically reduces SMOC2 gene expression in brachycephalic dogs. SMOC2 disruption affects the facial skeleton in a dose-dependent manner. The size effects of the associated SMOC2 haplotype are profound, accounting for 36% of facial length variation in the dogs we tested. Our data bring new focus to SMOC2 by highlighting its clinical implications in both human and veterinary medicine.

Postanaesthetic pulmonary oedema in a dog following intravenous naloxone administration after upper airway surgery. Natalie Bruniges, Clara Rigotti. Vet. Rec. Casereports. June 2017;5(2). Quote: A cavalier King Charles spaniel was anaesthetised for upper airway surgery. A constant rate infusion of fentanyl at 6 μg/kg/hour and top-up boluses (5 μg/kg in total) were used for intraoperative analgesia. Intermittent positive pressure ventilation (IPPV) was instituted due to tachypnoea and inability to maintain normocapnia. Apnoea and severe hypercapnia developed after cessation of IPPV. IPPV was recommenced for 10 min to reduce hypercapnia, after which spontaneous ventilation returned. The patient had not awakened 45 minutes after isoflurane was turned off and 0.01 mg/kg naloxone was administered intravenously due to suspected fentanyl-induced narcosis. Following immediate arousal, the patient vomited and suddenly developed symptoms and radiographic changes consistent with pulmonary oedema. General anaesthesia was reinduced and 1 mg/kg furosemide was administered intravenously. IPPV was started with application of positive end expiratory pressure in an air/oxygen mixture for 60 minutes. Recovery was uneventful. This is the first report of a dog developing pulmonary oedema following intravenous naloxone.

Elongated Soft Palate Resection with a Flexible Fiber CO2 Laser. Ray Arza. Clinician's Brief. October 2017;15(10):84.

Complications following laryngeal sacculectomy in brachycephalic dogs. J. R. Hughes, B. M. Kaye, A. R. Beswick, G. Ter Haar. J. Sm. Anim. Pract. October 2017. DOI:10.1111/jsap.12763. Quote: Objectives: To evaluate the effect of sacculectomy on the immediate postoperative complication rate in dogs affected with brachycephalic obstructive airway syndrome. Materials and Methods: Retrospective review of clinical records of brachycephalic dogs [limited to pugs, British bulldogs, and French bulldogs] with everted saccules that underwent surgery for brachycephalic obstructive airway syndrome between 2009 and 2014. Dogs were grouped as those having nares resection and staphylectomy only and those having nares resection, staphylectomy and laryngeal sacculectomy. Complications were scored as mild, moderate or severe. Results: In total, 37 dogs were included in the sacculectomy group and 44 in the comparator group. Dogs that had undergone sacculectomy were more likely to develop postoperative complications, with 18 of 37 developing complications, nine of which were moderate to severe. In the group without sacculectomy, nine of 44 dogs developed complications, of which one was severe. Different breed distribution between groups might also impact this outcome. Clinical Significance: The results suggest that sacculectomy might increase morbidity following brachycephalic airway surgery, but repeat studies are required to confirm this result. Further information is also required to determine whether the short-term risks of sacculectomy are outweighed by superior long-term functional outcome.

Anatomical features of the optic canal and the cephalic index in the cranial bone of healthy dogs. Y Ichikawa, N Kanemaki. Vet. Ophthal. October 2017. DOI: 10.1111/vop.12519; E-14. Quote: Purpose: We studied the anatomical features of the optical canal among brachycephalic, mesocephalic, and dolichocephalic dogs, which are characterized by cephalic indexes, by analyzing computed tomography (CT) images of the head in healthy dogs. Methods: Thirty-two adult healthy dogs were divided into three groups. The eight brachycephalic dogs included three Cavalier King Charles spaniels, two French bulldogs and Chihuahuas, and one Shih Tzu. The 13 mesocephalic dogs included four American cocker spaniels and Cardigan Welsh corgis, two toy poodles and Yorkshire terriers, and one Labrador retriever. The 11 dolichocephalic dogs included nine miniature dachshunds, one Great Dane and Shetland sheepdog. OsiriX Lite software (v.8.0.2, Picmeo SARL, Switzerland) was used to measure the length and diameter of the optic canal and the angle of the paired canals, and cephalic index, with the CT images of the heads. Values among the groups were analyzed using a post-hoc test. Results: Stockard’s and Evans’s cephalic index in the brachycephalic group were 94.3 ± 13.7 and 79.4 ± 12.0, respectively, and significantly higher than those of the mesocephalic and dolichocephalic groups. The angle of paired canals in the brachycephalic, mesocephalic, and dolichocephalic groups was 103.1 ± 12.8, 82.9 ± 8.1, and 79.7 ± 5.7 degrees, respectively. There was a positive correlation between the angle of optic canals and the cephalic index. There was no significant difference in the length and diameter of the optic canal among the groups. Conclusions: The positioning of the optic canal varies with cranial morphology in dogs.

Brachycephaly-related diseases. Gert Ter Haar, Rick F. Sánchez. Vet. Focus. November 2017;3:15-22. Quote: Key Points: • Small brachycephalic breeds are becoming increasingly popular, but these dogs have several anatomical features that predispose them to various health problems and are a concern for animal welfare. • Brachycephalic dogs are widely recognized to suffer from Brachycephalic Obstructive Airway Syndrome, which is due to various abnormalities in the upper respiratory tract. • Various gastrointestinal signs, including dysphagia and hiatus hernia, are also commonly seen in brachycephalic breeds. • Brachycephaly leads to changes in the ear canals and tympanic bullae, predisposing dogs to various ear diseases and reduced hearing. • Ocular disorders including pigmentary keratitis and corneal ulcers are commonly seen in Pugs and other brachycephalic breeds.

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2018

Magnetic resonance imaging evaluation of olfactory bulb angle and soft palate dimensions in brachycephalic and nonbrachycephalic dogs. David A. Barker, Carlos Rubiños, Olivier Taeymans, Jackie L. Demetriou. Amer. J. Vet. Res. February 2018;79(2):170-176. Quote: Objective: To determine from MRI measurements whether soft palate length (SPL) and thickness are correlated in dogs, evaluate the association between the olfactory bulb angle (OBA) and degree of brachycephalia, and determine the correlation between soft palate–epiglottis overlap and OBA in dogs. Animals: 50 brachycephalic [including 5 cavalier King Charles spaniels] and 50 nonbrachycephalic client-owned dogs without abnormalities of the head. Procedures: Medical records and archived midsagittal T2-weighted MRI images of brachycephalic and nonbrachycephalic dogs' heads were reviewed. Group assignment was based on breed. Data collected included weight, SPL and thickness, OBA, and the distance between the caudal extremity of the soft palate and the basihyoid. Soft palate length and thickness were adjusted on the basis of body weight. Results: Brachycephalic dogs had significantly thicker soft palates and lower OBAs, compared with findings for nonbrachycephalic dogs. There was a significant negative correlation (r2 = 0.45) between OBA and soft palate thickness. The correlation between SPL and OBA was less profound (r2 = 0.09). The distance between the caudal extremity of the soft palate and the basihyoid was shorter in brachycephalic dogs than in nonbrachycephalic dogs. The percentage of epiglottis–soft palate overlap significantly decreased with increasing OBA (r2 = 0.31). Conclusions & Clinical Relevance: Results indicated that MRI images can be consistently used to assess anatomic landmarks for measurement of SPL and thickness, OBA, and soft palate-to-epiglottis distance in brachycephalic and nonbrachycephalic dogs. The percentage of epiglottis–soft palate overlap was significantly greater in brachycephalic dogs and was correlated to the degree of brachycephalia.

The prevalence of dynamic pharyngeal collapse is high in brachycephalic dogs undergoing videofluoroscopy. Rachel E. Pollard, Lynelle R. Johnson, Stanley L.Marks. Vet. Radial Ultrasound. April 2018; doi: 10.1111/vru.12655. Quote: The aim of this retrospective study was to determine the frequency of pharyngeal collapse ina large group of brachycephalic dogs undergoing videofluoroscopic assessment of swallowingor airway diameter. We hypothesized that brachycephalic dogs would have pharyngeal collapsemore frequently than dolichocephalic or mesocephalic dogs with or without airway collapse. Themedical records database was searched for brachycephalic dogs undergoing videofluoroscopyof swallowing or airway diameter between January 1, 2006 and December 31, 2015. A cohortof dolichocephalic/mesocephalic dogs with videofluoroscopically confirmed airway collapse wasage and time matched for comparison. A control group of dolichocephalic/mesocephalic dogsthat did not have documented airway collapse was also evaluated. All fluoroscopic studies wereassessed by a board certified veterinary radiologist for the presence and degree of pharyngealcollapse. Results demonstrate that pharyngeal collapsewas significantly more common in brachycephalicdogs (58/82; 72%) than in nonbrachycephalic dogs with (7/25; 28%) and without (2/30;7%) airway collapse. Pharyngeal collapse is more prevalent in brachycephalic dogs undergoingvideofluoroscopy than in dolichocephalic/mesocephalic dogs with or without airway collapse.

Sleep disordered breathing in the Cavalier King Charles Spaniel: a case series. Tom Hinchliffe, Nai-Chieh Liu, Jane Ladlow. BSAVA Congress 2018 Proceedings. April 2018;pp. 479-480. Quote: Objectives: Obstructive sleep apnoea has been widely investigated in human medicine, but relatively few studies have described this condition in veterinary species; to date it has only been reported in English Bulldogs, French Bulldogs and Pugs. The aim of this study was to report the clinical features, diagnosis, management and outcome of five cases of obstructive sleep apnoea in the Cavalier King Charles Spaniel (CKCS). Methods: A retrospective case series was created using hospital records over five years, followed up via recheck appointments and a telephone questionnaire. The inclusion criteria consisted of CKCSs presenting primarily for sleep disorders, which were treated surgically for obstructive anatomical pathology. Results: All five cases presented with stertorous breathing, choking and apnoea during sleep. All cases had a number of co-morbidities: 5/5 had eosinophilic stomatitis and otitis media, 4/5 had mitral valve insufficiency and 3/5 had syringomyelia. CT and rhinoscopy revealed that 5/5 had aberrant nasal turbinates, nasal septal deviation and soft palate thickening and 3/5 had nasopharyngeal thickening and tracheal collapse. Treatment consisted of a combination of laser turbinectomy, folding flap palatoplasty, tonsillectomy, laryngeal sacculectomy and cuneiform process resection. All cases had an improvement in both the incidence and severity of sleep apnoea within a week, with 4/5 cases achieving complete resolution. Conclusions: This study concludes that obstructive sleep apnoea is a condition that may affect the CKCS and all five cases described here improved following surgical intervention. Consequntly, sleep disordered breathing is a presentation that veterinary surgeons should be aware of in this breed. (See this May 2019 article on the same study.)

Long-term outcome of permanent tracheostomy in 15 dogs with severe laryngeal collapse secondary to brachycephalic airway obstructive syndrome. Matteo Gobbetti, Stefano Romussi, Paolo Buracco, Valerio Bronzo, Samuele Gatti, Matteo Cantatore. Vet. Surg. June 2018;doi:10.1111/vsu.12903. Quote: Objective: To report the long‐term outcome of permanent tracheostomy for the management of severe laryngeal collapse secondary to brachycephalic airway obstructive syndrome. Study design: Retrospective case series. Animals: Fifteen brachycephalic dogs with severe laryngeal collapse [including one cavalier King Charles spaniel] treated with permanent tracheostomy. Methods: Follow-up data were obtained from medical records or via telephone conversation with the owners. The Kaplan-Meier estimator was used to calculate median survival time. Death was classified as related or unrelated to tracheostomy surgery. Complications were classified as major when they were life-threatening or required revision surgery. Owners were asked to classify the postoperative quality of life as improved, unchanged, or worse and the management of the stoma as simple or demanding. Results: The median survival time was 100 days [the CKCS survied 143 days]. Major complications were diagnosed in 12 of 15 (80%) dogs, resulting in death in 8 (median survival time 15 days) and revision surgery in 4 dogs [including the CKCS]. Seven of 15 (47%) dogs died of unrelated causes [including the CKCS] or were alive at the end of the study (median survival time 1982 days). The postoperative quality of life of 9 dogs was judged as markedly improved [including the CKCS]. Stoma management was defined as simple in 8 dogs and demanding in 4. Conclusion: Permanent tracheostomy was associated with a high risk of complications and postoperative death in brachycephalic dogs. However, long-term survival (exceeding 5 years) with a good quality of life was documented in 5 of 15 dogs [including the CKCS]. Clinical significance: Permanent tracheostomy is a suitable salvage option in brachycephalic dogs with severe laryngeal collapse that did not improve following more conservative surgeries.

Risk of anesthesia-related complications in brachycephalic dogs. Michaela Gruenheid, Turi K. Aarnes, Mary A. McLoughlin, Elaine M. Simpson, Dimitria A. Mathys, Dixie F. Mollenkopf, Thomas E. Wittum. JAVMA. August 2018;253(3):301-306. Quote: Objective: To determine whether brachycephalic dogs were at greater risk of anesthesia-related complications than nonbrachycephalic dogs and identify other risk factors for such complications. Design: Retrospective cohort study. Animals: 223 client-owned brachycephalic dogs [none were cavalier King Charles spaniels] undergoing general anesthesia for routine surgery or diagnostic imaging during 2012 and 223 nonbrachycephalic client-owned dogs matched by surgical procedure and other characteristics. Procedures: Data were obtained from the medical records regarding dog signalment, clinical signs, anesthetic variables, surgery characteristics, and complications noted during or following anesthesia (prior to discharge from the hospital). Risk of complications was compared between brachycephalic and nonbrachycephalic dogs, controlling for other factors. Results: Perianesthetic (intra-anesthetic and postanesthetic) complications were recorded for 49.1% (n = 219) of all 446 dogs (49.8% [111/223] of brachycephalic and 48.4% [108/223] of nonbrachycephalic dogs), and postanesthetic complications were recorded for 8.7% (39/446; 13.9% [31/223] of brachycephalic and 3.6% [8/223] of nonbrachycephalic dogs). Factors associated with a higher perianesthetic complication rate included brachycephalic status and longer (vs shorter) duration of anesthesia; the risk of perianesthetic complications decreased with increasing body weight and with orthopedic or radiologic procedures (vs soft tissue procedures). Factors associated with a higher postanesthetic complication rate included brachycephalic status, increasing American Society of Anesthesiologists status, use of ketamine plus a benzodiazepine (vs propofol with or without lidocaine) for anesthetic induction, and invasive (vs noninvasive) procedures. Conclusions & Clinical Relevance: Controlling for other factors, brachycephalic dogs undergoing routine surgery or imaging were at higher risk of peri- and postanesthetic complications than nonbrachycephalic dogs. Careful monitoring is recommended for brachycephalic dogs in the perianesthetic period.

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2019

Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary Specialists. Anne Fawcett, Vanessa Barrs, Magdoline Awad, Georgina Child, Laurencie Brunel, Erin Mooney, Fernando Martinez-Taboada, Beth McDonald, Paul McGreevy. Animals. January 2019;9(1):3. Quote: This article, written by veterinarians whose caseloads include brachycephalic dogs, argues that there is now widespread evidence documenting a link between extreme brachycephalic phenotypes and chronic disease, which compromises canine welfare. This paper is divided into nine sections exploring the breadth of the impact of brachycephaly on the incidence of disease, as indicated by pet insurance claims data from an Australian pet insurance provider, the stabilization of respiratory distress associated with brachycephalic obstructive airway syndrome (BOAS), challenges associated with sedation and the anaesthesia of patients with BOAS; effects of brachycephaly on the brain and associated neurological conditions, dermatological conditions associated with brachycephalic breeds, and other conditions, including ophthalmic and orthopedic conditions, and behavioural consequences of brachycephaly. In the light of this information, we discuss the ethical challenges that are associated with brachycephalic breeds, and the role of the veterinarian. ... Petsure Australia has collected relevant prevalent and actuarial data over the years, in the process of administering its core business of providing pet insurance policies. This includes the following brachycephalic breeds from their database in its ongoing in-house study: Affenpinscher, American Bulldog, Australian Bulldog, Australian Bulldog Miniature, Boston Terrier, Boxer, British Bulldog, Cavalier King Charles Spaniel (CKCS), Dogue De Bordeaux, French Bulldog, Griffon, Griffon Brabancon, Griffon Bruxellois, Lhasa Apso, Mastiff, Neopolitan Mastiff, Pekingese, Pug and Shih Tzu. ... In addition, individual breeds have specific dermatological disorders, including primary secretory otitis media (PSOM) in the Cavalier King Charles Spaniel. ... CM has been described most commonly in the CKCS, and is reported to occur in 100%of dogs of this breed. ... CKCSs and Griffons Bruxellois are highly predisposed to SM, with a prevalence in dogs without recognised clinical signs being estimated at 25% at 12 months of age, 70% at six years or older in CKCSs ... (of varying ages). The incidence of dogs showing clinical signs associated with CM and/or SM is much lower. CM and SM have a moderately high heritability in CKCSs, and genetic factors are likely in other affected breeds and many of their crosses. SM is almost certainly associated directly with skull conformation. The mode of inheritance is unclear, but it does not appear to be simple. Phenotypic screening of CKCSs and Griffons Bruxellois in the last 10 years seems to have reduced the incidence of severely affected dogs in breeding lines, where screening with magnetic resonance imaging (MRI) has been undertaken, but has not eliminated the condition. ... Two significant risk factors that are associated with the development of CM/SM in the conformation of the CKCS are the extent of the brachycephaly, and the distribution of the cranium (higher cephalic index with a broader, shorter head and rostrocaudal doming. ... Brachycephalic breeds may experience a higher incidence of orthopaedic conditions. ... The prevalence of patellar luxation was ... 3.8% in CKCS ..., compared with an overall prevalence of 1.3%. ... In summary, dogs with BOAS do not enjoy freedom from discomfort, nor freedom from pain, injury, and disease, and they do not enjoy the freedom to express normal behaviour. According to both deontological and utilitarian ethical frameworks, the breeding of dogs with BOAS cannot be justified, and further, cannot be recommended, and indeed, should be discouraged by veterinarians.

Sleep-disordered breathing in the Cavalier King Charles spaniel: A case series. Tom A. Hinchliffe, Nai-Chieh Liu, Jane Ladlow. Vet. Surg. May 2019;48(4):497-504. Quote: Objective: To describe sleep-disordered breathing (SDB) in the Cavalier King Charles spaniel (CKCS). Study design Retrospective case series. Animals: Five client-owned dogs referred for SDB. Methods: Medical records were reviewed including recheck appointments and routine preoperative and postoperative questionnaires. Whole-body barometric plethysmography was used to categorize SDB. Results: All dogs presented with multiple episodes of stertorous breathing, choking, and apnea during sleep. Severe nasal septal deviation, aberrant nasal turbinates, and soft palate elongation and thickening were noted on computed tomography and rhinoscopy of each dog. Whole-body barometric plethysmography measurements during sleep (in 3 dogs) documented periods of choking, snoring, and apnea. Treatment combined laser turbinectomy, folding flap palatoplasty, tonsillectomy, laryngeal sacculectomy, and cuneiform process resection. All dogs improved in terms of incidence and severity of sleep apnea within 1 week, with 4 of 5 dogs achieving complete resolution. Conclusion: The objective measurements used to characterize SDB in this population of CKCS provided some evidence to support an obstructive cause for this condition, which improved with surgical treatment. Clinical significance Sleep-disordered breathing in the CKCS is a different clinical presentation of brachycephalic obstructive airway syndrome. Our finding of intranasal abnormalities in these 5 dogs with SDB provides justification for future research into its clinical significance. (See this April 2018 abstract of the same study.)

Postoperative regurgitation in dogs after upper airway surgery to treat brachycephalic obstructive airway syndrome: 258 cases (2013-2017). Joy V. H. Fenner, Robert J. Quinn, Jackie L. Demetriou. Vet. Surgery. July 2019; doi: 10.1111/vsu.13297 Quote: Objective: To determine the incidence of and risk factors for regurgitation in dogs within 24 hours of surgical management of brachycephalic obstructive airway syndrome (BOAS). Study design: Retrospective single center study of dogs undergoing BOAS surgery over four years (2013-2017). Animals: Two hundred fifty-eight client-owned dogs referred for surgical intervention for BOAS. [20 cavalier King Charles spaniels -- 8%] Methods: Electronic medical records were searched for dogs that had undergone surgery for BOAS at a UK specialist referral hospital. Data were assessed by using univariable binomial logistic regression; confounding factors were then identified in a multivariable model. Results: There was an increase in the proportion of dogs that regurgitated while hospitalized preoperatively vs during the first 24 hours postoperatively, from 28 (10.9%) to 89 (34.5%), respectively (P<.0001). History of regurgitation (P =.017, odds ratio [OR] 2.539, 95% confidence interval [CI] 1.178-5.469) and age (P =.008, OR 0.712, 95% CI 0.553-0.916) were detected as risk factors for postoperative regurgitation. For every 1-year increase in age, the odds of experiencing postoperative regurgitation were reduced by 28.8%. [None of the CKCSs had any post-operative regurgitation.] Conclusion: Corrective surgery for BOAS was associated with a marked incidence of postoperative regurgitation. Younger dogs and those with a history of regurgitation were predisposed to postoperative regurgitation. Clinical significance: The increased frequency of regurgitation after surgical treatment of BOAS, especially in younger dogs, provides justification for counseling owners regarding this postoperative complication.

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2020

Brachycephalic airway syndrome: management of post-operative respiratory complications in 248 dogs. B Lindsay, D Cook, J-M Wetzel, S Siess, P Moses. Austral. Vet. J. February 2020; doi: 10.1111/avj.12926. Quote: Objective: As ownership of brachycephalic dog breeds rises, the surgical correction of components of brachycephalic airway syndrome (BAS) is increasingly recommended by veterinarians. This study's objective was to describe the incidence of, and strategies for the management of post-operative respiratory complications in brachycephalic dogs undergoing surgical correction of one or more components of BAS. Methods: Medical records of 248 brachycephalic dogs [42 cavalier King Charles spaniels (CKCS)(16.9%)]treated surgically for BAS were retrospectively reviewed for demographic information, procedures performed, post-operative complications and treatment implemented, hospitalisation time, and necessity for further surgery. Results: Pugs, Cavalier King Charles Spaniels and British Bulldogs were the most commonly encountered breeds. Dogs which experienced a complication were significantly older (mean was 5.5 years, compared with 4.1 years [P < 0.01]). ... CKCSs were found to present significantly older than the rest of the population (mean age 5.8 years). ... Table 1: Number of dogs with various compoments of brachycephalic airway syndrome treated surgically: Elongated soft palate - 242 dogs (97.6%); hyperplastic tonsillar tissue - 106 dogs (42.7%); everted saccules - 103 dogs (41.5%); stenotic nares - 97 dogs (39.1%). ... Fifty-eight dogs (23.4%) had complications which included: dyspnoea managed with supplemental oxygen alone (7.3%, n = 18), dyspnoea requiring anaesthesia and re-intubation (8.9%, n = 22), dyspnoea necessitating treatment with a temporary tracheostomy (8.9%, n = 22), aspiration pneumonia (4%, n = 10), and respiratory or cardiac arrest (2.4%, n = 6). Five of the 22 dogs requiring anaesthesia and re-intubation deteriorated 12 or more hours after post-surgical anaesthetic recovery. The overall mortality rate in this study was 2.4% (n = 6). Age, concurrent airway pathology, and emergency presentation significantly predicted post-operative complications. Conclusion: Our data show the importance of close monitoring for a minimum of 24 h following surgery by an experienced veterinarian or veterinary technician. Surgical intervention for BAS symptomatic dogs should be considered at an earlier age as an elective procedure, to reduce the risk of post-operative complications.

“Forever young” — Postnatal growth inhibition of the turbinal skeleton in brachycephalic dog breeds (Canis lupus familiaris). Franziska Wagner, Irina Ruf. Anat. Rec. May 2020; doi: 10.1002/ar.24422 Quote: In short snouted (brachycephalic) dogs (Canis lupus familiaris ), several genetic mutations cause postnatal growth inhibition of the viscerocranium. Thus, for example, the pug keeps a snub nose like that observed in neonate dogs in general. However, little is known how far intranasal structures like the turbinal skeleton are also affected. In the present study, we provide the first detailed morphological and morphometric analyses on the turbinal skeleton of pug, Japanese chin, pekingese, King Charles spaniel, and Cavalier. ... The brachycephalic King spaniel and the moderate brachycephalic to mesaticephalic Cavalier serve as an example for the reverse breeding, namely the elongation of the face. ... By this, the following hypotheses are evaluated: ... (c) the fast secondary elongation of the snout in the Cavalier exhibits a similar pattern to the pug in reverse. Based on the ancestral stage predetermined by the King spaniel, within the enlarged nasal cavity the still simplified turbinals of the Cavalier have a smaller IAT and a looser arrangement, that is, a smaller SDEN [turbinal surface density]. ... In order to elucidate how a shortened snout affects turbinal shape, size, and density, our sample covers different degrees of brachycephaly. Macerated skulls of 1 juvenile and 17 adult individuals [including 2 cavalier King Charles spaniels -- NMBE1059207 & NMBE1062998] were investigated by μCT and virtual 3D reconstructions. In addition, histological serial sections of two prenatal and one neonate whippet were taken into account. All investigated postnatal stages show three frontoturbinals and three ethmoturbinals similar to longer snouted breeds, whereas the number of interturbinals is reduced. The shape of the entire turbinal skeleton simplifies with decreasing snout length, that is, within a minimized nasal cavity the turbinals decrease proportionally in surface area and surface density due to a looser arrangement. We interpret these apparent reductions as a result of spatial constraint which affects postnatal appositional bone growth and the position of the turbinals inside the nasal cavity. The turbinal skeleton of brachycephalic dogs arrests at an early ontogenetic stage, corresponding with previous studies on the dermal bones. Hence, we assume an association between the growth of intranasal structures and facial elongation. ... Our current study proves that the medium snouted ancient pug ZMB_MAM 30980 and the Cavalier specimen correspond to this size relation, whereas the more extreme brachycephalic Toy dogs are similar to the juvenile pattern. ... The influence of ontogeny in association with facial length growth on the development of the turbinal skeleton further explains the latter's simple morphology in the short snouted modern pug on the one hand, and the complex shape in the moderate brachycephalic to mesaticephalic Cavalier on the other hand. As expected, the ancient Toy breeds (chin, pekingese, King spaniel, ancient pug) have a smaller IAT and lower SDEN than is reflected by the grundplan . Contrasting our other two hypotheses, fast evolutionary changes, like the artificial shortening (modern pug) or elongation (Cavalier) of the face, have no or little influence on the development of the turbinal skeleton. ... Our study clearly demonstrates that the rapid change of facial shape in dogs first affects the number of the least developed turbinals, especially the additional interturbinals. ... The species-specific number of fronto-, ethmo-, and prominent interturbinals is forced to develop within the smaller space of the shortened snout in brachycephalic dogs. ...The genetic mutations, which restrict the facial length growth in brachycephalic breeds, also affect the development of the turbinals and determine both, the endochondral ossification of the fetal cartilaginous turbinals as well as the intramembraneous ossification of their accessory lamellae. The reduced space within the nasal cavity effects directly the arrangement of the turbinal skeleton and forces certain parts to avoid the restricted space as aberrant turbinals.

Sleep in the dog: comparative, behavioral and translational relevance. Róbert Bódizs1, Anna Kis, Márta Gácsi, József Topál. Current Opin. Behavior Sci. June 2020; doi: 10.1016/j.cobeha.2019.12.006. Quote: The dog (Canis familiaris) is a promising non-invasive translational model of human cognitive neuroscience including sleep research. Studies on the relationship between sleep and cognition in dogs and other canines are only just emerging, but still very scarce. Here we provide insight into canine sleep and sleep-related physiological and cognitive/behavioral phenomena. We show that dogs do not only fulfil all behavioral and polygraphic criteria of sleep, but are characterized by sleep homeostasis, diurnal pattern of activity, circadian rhythms, ultradian sleep cycles, socio-ecologically and environmentally shaped wake-sleep structure, sleep-related memory improvement, as well as specific sleep disorders. Developmental patterns of sleep-related physiological indices, as well as parallel trends in age-dependent changes in cognition and sleep were evidenced in dogs. • All behavioral and polygraphic criteria of (NREM and REM) sleep are met in the dog. • Dogs are diurnal: weak circadian modulation and assumed adaptation to human rhythms. • Pre-sleep experiences, location and socio-ecological factors affect canine sleep. • Sleep may contribute to dogs’ memory consolidation. • Development and aging affect sleep and cognition in dogs. ... Sleep disordered breathing is associated with episodes of O2 desaturation and loud snoring during sleep, as well as daytime hypersomnolence, sluggishness, and shortened sleep latency. The English bulldog, the Cavalier King Charles spaniel, as well as other brachycephalic breeds are most commonly affected. The English bulldog has been proposed as a natural model of sleep-disordered breathing.

Dorsal offset rhinoplasty for treatment of stenotic nares in 34 brachycephalic dogs. Vanna M. Dickerson, Corinne M. B. Dillard, Janet A. Grimes, Mandy L. Wallace, Jonathan F. McAnulty, Chad W. Schmiedt. Vet. Surg. August 2020; doi: 10.1111/vsu.13504. Quote: Objective: To describe the technique, outcome, and owner satisfaction associated with dorsal offset rhinoplasty (DOR) to treat stenotic nares in brachycephalic dogs. Study design: Retrospective case series. Animals: Thirty-four client-owned dogs. ... The most common breed was the English bulldog (n = 18), followed by the French bulldog (n = 6), Boston terrier (n = 4), pug (n = 2), shih tzu (n = 2), Japanese chin (n = 1), and Cavalier King Charles spaniel (n = 1). ... Methods: Medical records of dogs treated with DOR at a veterinary teaching hospital over a 6-year period were identified. Dorsal offset rhinoplasty was defined as removal of a dorsal wedge of nasal planum from each naris with apposition of the rostral abaxial tissue to the caudal axial tissue, resulting in translocation of the alar cartilage in both median and dorsal planes. Immediate and postoperative complications were recorded. Owners were asked to report any complications with healing of the nares and to score their satisfaction with the appearance of the nares. Results: Thirty-four dogs met the inclusion criteria. Twenty-nine (85%) dogs were examined a median of 402.5 days (range, 23-2042) postoperatively, with no major complications related to the rhinoplasty recorded. Eighteen owners responded a median of 701 days (range, 37-1622) postoperatively. One owner reported that self-trauma led to collapse of one naris. One owner reported collapse of both nares within 4 years; timing and cause were unknown. Sixteen of 17 responding owners reported that they were very satisfied with the outcome of the rhinoplasty. The owner of the dog with the collapsed naris was very unsatisfied. One owner did not provide a satisfaction score. Conclusion: Owners were generally highly satisfied with DOR, and complications were uncommon. Clinical significance: This report describes an alternate technique to treat stenotic nares.

Unravelling the health status of brachycephalic dogs in the UK using multivariable analysis. D. G. O’Neill, C. Pegram, P. Crocker, D. C. Brodbelt, D. B. Church, R. M. A. Packer. Sci. Rep. October 2020; doi: 10.1038/s41598-020-73088-y. Quote: Brachycephalic dog breeds are regularly asserted as being less healthy than non-brachycephalic breeds. Using primary-care veterinary clinical data, this study aimed to identify predispositions and protections in brachycephalic dogs and explore differing inferences between univariable and multivariable results. All disorders during 2016 were extracted from a random sample of 22,333 dogs within the VetCompass Programme from a sampling frame of 955,554 dogs under UK veterinary care in 2016. ... There were 4,169 (18.74%) brachycephalic and 18,079 (81.26%) non-brachycephalic types. ... The brachycephalic group included 34 individual breeds ... The most common brachycephalic breeds were Chihuahua (n = 955, 22.91%), Shih-tzu (795, 19.07%) and Cavalier King Charles Spaniel (435, 10.43%). ... The degree (or severity) of brachycephaly varies between breeds (a bulldog may be considered as more severely brachycephalic than a Cavalier King Charles Spaniel) but there can also be considerable variation in brachycephaly within breeds. Shifting the median severity of brachycephaly towards a longer skull shape within breeds has been suggested as one option to reduce the prevalence of disorders directly linked to brachycephaly while still retaining these breeds within the overall dog population. ... Univariable and multivariable binary logistic regression modelling explored brachycephaly as a risk factor for each of a series of common disorders. Brachycephalic dogs were younger, lighter and less likely to be neutered than mesocephalic, dolichocephalic and crossbred dogs. Brachycephalic differed to non-brachycephalic types in their odds for 10/30 (33.33%) common disorders. Of these, brachycephalic types were predisposed for eight disorders and were protected for two disorders. ...The most common precise disorders (i.e. greatest prevalence) in the brachycephalic types were periodontal disease (n = 485, prevalence = 11.63%), otitis externa (303, 7.27%), obesity (266, 6.38%), anal sac impaction (249, 5.97%), overgrown nail(s) (212, 5.09%), diarrhoea (143, 3.43%) and heart murmur (3.43%). There were eight precise disorders with the higher odds in multivariable logistic regression analysis (i.e. disorder predisposition) for brachycephalic types compared with non-brachycephalic types: corneal ulceration, heart murmur, umbilical hernia, pododermatitis, skin cyst, patellar luxation, otitis externa and anal sac impaction. Two precise disorders had reduced odds for brachycephalic types in multivariable analysis: undesirable behaviour and claw injury. ...  This study provides strong evidence that brachycephalic breeds are generally less healthy than their non-brachycephalic counterparts. Results from studies that report only univariable methods should be treated with extreme caution due to potential confounding effects that have not been accounted for during univariable study design or analysis. ... Conclusion: This study provides strong evidence to support the common assertion that brachycephalic breeds are generally less healthy than their non-brachycephalic counterparts in relation to total disorder counts and specific common conditions recorded. Potential solutions to some of these health problems are likely to require conformational change to current skull shapes averages for many breeds; however, many other health problems will require targeted action at the individual breed level, owing to large differences in individual breed predispositions to disorders. Results from studies that report only univariable methods should be treated with extreme caution due to potential confounding effects that have not been accounted for during study design or analysis.

“Forever young” — Postnatal growth inhibition of the turbinal skeleton in brachycephalic dog breeds (Canis lupus familiaris). Franziska Wagner, Irina Ruf. Anat. Rec. December 2020; doi: 10.1002/ar.24422. Quote: In short snouted (brachycephalic) dogs (Canis lupus familiaris), several genetic mutations cause postnatal growth inhibition of the viscerocranium [facial bones]. Thus, for example, the pug keeps a snub nose like that observed in neonate dogs in general. However, little is known how far intranasal structures like the turbinal [nasal] skeleton are also affected. ... The brachycephalic King spaniel and the moderate brachycephalic to mesaticephalic Cavalier serve as an example for the reverse breeding, namely the elongation of the face. ... In the present study, we provide the first detailed morphological and morphometric analyses on the turbinal skeleton of pug, Japanese chin, pekingese, King Charles spaniel, and Cavalier. In order to elucidate how a shortened snout affects turbinal shape, size, and density, our sample covers different degrees of brachycephaly. Macerated skulls of 1 juvenile and 17 adult individuals [including two cavalier King Charles spaniels] were investigated by μCT and virtual 3D reconstructions. In addition, histological serial sections of two prenatal and one neonate whippet were taken into account. All investigated postnatal stages show three frontoturbinals and three ethmoturbinals similar to longer snouted breeds, whereas the number of interturbinals is reduced. The shape of the entire turbinal skeleton simplifies with decreasing snout length, that is, within a minimized nasal cavity the turbinals decrease proportionally in surface area and surface density due to a looser arrangement. We interpret these apparent reductions as a result of spatial constraint which affects postnatal appositional bone growth and the position of the turbinals inside the nasal cavity. The turbinal skeleton of brachycephalic dogs arrests at an early ontogenetic stage, corresponding with previous studies on the dermal bones. Hence, we assume an association between the growth of intranasal structures and facial elongation. ... Contrasting our other two hypotheses, fast evolutionary changes, like the artificial shortening (modern pug) or elongation (Cavalier) of the face, have no or little influence on the development of the turbinal skeleton.

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2021

Sleep disorders in dogs: A pathophysiological and clinical review. Alejandra Mondino, Luis Delucchi, Adam Moeser, Sofía Cerdá-González, Giancarlo Vanini. Topics in Companion Anim. Med. February 2021; doi: 10.1016/j.tcam.2021.100516. Quote: Sleep is a fundamental process in mammals, including domestic dogs. Disturbances in sleep affect physiological functions like cognitive and physical performance, immune response, pain sensation and increase the risk of diseases. In dogs, sleep can be affected by several conditions, with narcolepsy, REM sleep behavior disorder and sleep breathing disorders being the most frequent causes. Furthermore, sleep disturbances can be a symptom of other primary diseases where they can contribute to the worsening of clinical signs. This review describes reciprocally interacting sleep and wakefulness promoting systems and how their dysfunction can explain the pathophysiological mechanisms of sleep disorders. ... Cavalier King Charles Spaniel (CKCS) ... can be affected with SBD [sleep-related breathing disorders]. The severity of the disorder can range from partial obstructive snoring to apnea. ... CKCS, one of the breeds affected by SDB, also have a high prevalence of Chiari-like malformations (Caudal Occipital Malformation Syndrome, (COMS). In fact, 60% of the CKCS with SDB studied by Hinchliffe et al., (2018) had syringomyelia, which can occur secondary to COMS among other craniocervical junction disorders. However, these dogs all responded well to surgical interventions of the upper airway, suggesting that the SDB was at least partially explained by OSA [obstructive sleep apnea]. In dogs with OSA the anatomic features responsible for the disorder should be determined by complete oropharyngeal examination, endoscopy, and computed tomography as needed. ... Additionally, this work discusses the clinical characteristics, diagnostic tools and available treatments for these disorders while highlighting areas in where further studies are needed so as to improve their treatment and prevention.

The Need for Head Space: Brachycephaly and Cerebrospinal Fluid Disorders. Clare Rusbridge, Penny Knowler. Life. February 2021; doi: 10.3390/life11020139. Quote: Brachycephalic dogs remain popular, despite the knowledge that this head conformation is associated with health problems, including airway compromise, ocular disorders, neurological disease, and other co-morbidities. There is increasing evidence that brachycephaly disrupts cerebrospinal fluid [CSF] movement and absorption, predisposing ventriculomegaly, hydrocephalus, quadrigeminal cistern expansion, Chiari-like malformation, and syringomyelia. In this review, we focus on cerebrospinal fluid physiology and how this is impacted by brachycephaly, airorhynchy, and associated craniosynostosis [premature closure of cranial sutures, preventing continued growth to accommodate the growing size of the brain]. ... As the majority of CSF is absorbed through lymphatics in the skull base and via the olfactory bulbs, the balance between CSF production and absorption may be impacted by craniofacial hypoplasia and cranial base shortening. ... Respiration drives CSF movement through the ventricular system. ... [O]ne of the most important skull base foramen [openings] is the jugular, situated between the temporal and occipital bone. The jugular foramen provides passage to cranial nerves IX, X, XI, sigmoid sinus, and lymphatics. Cavalier King Charles spaniels with syringomyelia associated with Chiari-like malformation have smaller volume jugular foramina compared to Cavalier King Charles spaniels without syringomyelia. However, direct causality between smaller jugular foramen and syringomyelia has not been proven. ... Cavalier King Charles spaniels with syringomyelia associated with Chiari malformation have reduced volume caudal cranial fossa dorsal sinuses. ... Dogs and cats with neonatal characteristics of a reduced muzzle and brachycephaly have impaired CSF circulation, which predisposes ventriculomegaly, hydrocephalus, quadrigeminal cistern expansion, Chiari-like malformation associated pain, and syringomyelia. Reduction of the lymphatic absorption of CSF through the nasal and skull base lymphatics, in conjunction with restriction of CSF movement through the lateral apertures and craniocervical junction, are hypothesized to be key features. Cranial venous stenosis, spinal canal conformation, chronic intermittent hypoxia, and thoracic cavity pressure gradients may contribute. The ethics of choosing to breed animals with this predisposition is questionable, despite their popularity as companion animals. Education of the pet-buying public, avoiding breeding extreme animals, and screening at-risk breeding stock is recommended.

Management of sleep disordered breathing in a dog using continuous positive airway pressure. Waylon Wiseman, A. Rosenblatt, M. Kunga. Aust. Vet. Pract. April 2021;51(1):19-25. Quote: A 4-year-old Cavalier King Charles spaniel presented for evaluation of disruptive apnoeic episodes, experienced every 10-15 minutes during sleep. Surgical intervention included bilateral tonsillectomy, bilateral laryngeal sacculectomy, and unilateral cricoarytenoid lateralisation. Minimal improvement in the frequency and severity of episodes of sleep disordered breathing were noted. ... We hypothesise that our patientcontinued to suffer SDB, despite corrective airway surgery with good clinical response while awake, due to DPC when sleeping, secondary to muscle hypotonia as seen in humans. ... The patient was subsequently fitted with a continuous positive airway pressure [CPAP] device at night and responded well to this intervention, allowing the dog to sleep through the night. Four years after the initial presentation, the patient underwent fluoroscopic large airway assessment and was diagnosed with dynamic pharyngeal collapse [DPC]. ... We then retrospectively confirmed partial pharyngeal collapse using videofluoroscopy. ... To the authors’ knowledge, this is the first report of the use of continuous positive airway pressure in the management of sleep disordered breathing in dogs and represents a novel management strategy for dogs suffering from this condition that respond poorly to airway surgery.

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2022

Nasal Septum Deviation in dog breeds predisposed to Chiari-like malformation associated pain and syringomyelia. Clare Rusbridge, J. R. Rusbridge. BSAVA Congress 2022. March 2022. Quote: Nasal Septum deviation in breeds predisposed to Chiari-like malformation associated pain and syringomyelia. Objectives: Nasal septum deviation (NSD) and Chiari-like malformation pain and syringomyelia (CMSM) are common in flat-faced brachycephalic dogs. NSD may be clinically irrelevant but has been associated with sleep disordered breathing (SDB) in humans and dogs. SDB affects glymphatic drainage of cerebrospinal fluid which could predispose CMSM. This study investigated possible correlation between NSD and CMSM Methods Study population - 76 dogs with head CT [computed tomography] and known CMSM status (based on MRI and medical history). Comprising 53 CKCS [cavalier King Charles spaniels] (70%) (7 CM-N [CM-clinically normal] i.e. MRI determined breed-associated CM but clinically normal; 14 with CM-P [CM-associated pain] but no SM; 32 with SM); 12 Chihuahua (5 MRI and clinically normal, 7 with SM); 11 other brachycephalic toy dog breeds and crosses (10 with SM). Transverse CT of the nasal cavity in bone windows was reviewed. Presence of a NSD was recorded. Previously described method of determining the angle of NSD was not reproducible and consequently abandoned. The NSD ratio calculated (maximum distance of NSD from midline/ distance from midline to nasal cavity wall). Results NSD was almost ubiquitous; Only 3 dogs had a midline nasal septum without deviation (1 Chihuahua, 1 CKCS, 1 Cavapoo; all 3 were CMSM affected). There was no correlation between NSD ratio and CMSM (signs of pain or presence of syringomyelia). Impact NSD is common in dog breeds predisposed to CMSM. Care should be taken before attributing clinical relevance. Association of NSD to CMSM is unproven. More extreme brachycephaly is associated with both NSD, CM-P and SM and therefore the conditions may co-exist. Airway obstruction, SDB and apnoea may be relevant in the pathogenesis of CMSM or be a important comorbidity. More sophisticated methods of investigation are recommended for example polysomnography to monitor respiratory effort.

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2023

Echocardiographic parameters in French Bulldogs, Pugs and Boston Terriers with brachycephalic obstructive airways syndrome. M. Brložnik, A. Nemec Svete, V. Erjavec & A. Domanjko Petric. BMC Vet. Res. February 2023; doi: 10.1186/s12917-023-03600-9. Quote: Background: In this prospective study, we hypothesized that dogs with signs of brachycephalic obstructive airway syndrome (BOAS) would show differences in left and right heart echocardiographic parameters compared with brachycephalic dogs without signs of BOAS and non-brachycephalic dogs. Result: We included 57 brachycephalic (30 French Bulldogs, 15 Pugs, and 12 Boston Terriers) and 10 non-brachycephalic control dogs. Brachycephalic dogs had significantly higher ratios of the left atrium to aorta and mitral early wave velocity to early diastolic septal annular velocity; smaller left ventricular (LV) diastolic internal diameter index; and lower tricuspid annular plane systolic excursion index, late diastolic annular velocity of the LV free wall, peak systolic septal annular velocity, late diastolic septal annular velocitiy, and right ventricular global strain than non-brachycephalic dogs. ... French Bulldogs: LA/Ao: 1.56 (1.44-1.60); Pugs: LA/Ao: 1.49 (1.45-1.62); Boston Terriers: LA/Ao: 1.55 (1.50-1.68). ... French Bulldogs with signs of BOAS had a smaller diameter of the left atrium index and right ventricular systolic area index; higher caudal vena cava at inspiration index; and lower caudal vena cava collapsibility index, late diastolic annular velocity of the LV free wall, and peak systolic annular velocity of the interventricular septum than non-brachycephalic dogs. Conclusions: ... The results of this study showed significant differences in echocardiographic parameters between the dogs of the three brachycephalic breeds and non-brachycephalic dogs. In addition, there were significant differences in echocardiographic parameters between dogs with and without signs of BOAS. ... We found significant differences in echocardiographic parameters between dogs of the three brachycephalic breeds and non-brachycephalic dogs, implying that breed-specific echocardiographic reference values should be used in clinical practice. In addition, significant differences were observed between brachycephalic dogs with and without signs of BOAS. The observed echocardiographic differences suggest higher right heart diastolic pressures affecting right heart function in brachycephalic dogs with and without signs of BOAS, and several of the differences are consistent with findings in OSA patients. Most of the changes of the heart morphology and function can be attributed to brachycephaly alone and not to the symptomatic stage.

Description of a novel method for detection of sleep-disordered breathing in brachycephalic dogs. Iida Niinikoski, Sari-Leena Himanen, Mirja Tenhunen, Liisa Lilja-Maula, Minna M. Rajamäki. J. Vet. Intern. Med. May 2023; doi: 10.1111/jvim.16783. Quote: Background: Sleep-disordered breathing (SDB), defined as any difficulty in breathing during sleep, occurs in brachycephalic dogs. Diagnostic methods for SDB in dogs require extensive equipment and laboratory assessment. Objectives: To evaluate the usability of a portable neckband system for detection of SDB in dogs. We hypothesized that the neckband is a feasible method for evaluation of SDB and that brachycephaly predisposes to SDB. Animals: Twenty-four prospectively recruited client-owned dogs: 12 brachycephalic dogs [including 9 French bulldogs and 1 cavalier King Charles spaniel] and 12 control dogs of mesocephalic or dolicocephalic breeds. Methods: Prospective observational cross-sectional study with convenience sampling. Recording was done over 1 night at each dog's home. The primary outcome measure was the obstructive Respiratory Event Index (OREI), which summarized the rate of obstructive SDB events per hour. Additionally, usability, duration of recording, and snore percentage were documented. Results: Brachycephalic dogs had a significantly higher OREI value (Hodges-Lehmann estimator for median difference = 3.5, 95% confidence interval [CI] 2.2-6.8) and snore percentage (Hodges-Lehmann estimator = 34.2, 95% CI 13.6-60.8) than controls. A strong positive correlation between OREI and snore percentage was detected in all dogs (rs = .79). ... The results would potentially be different if the BD [brachycephalic dog] group consisted of dogs with longer snouts such as the Bullmastiff and the Cavalier King Charles Spaniel. However, in addition to the laryngeal area, also obstruction of the nasal cavity can result in SDB, as documented in the Cavalier King Charles Spaniel. ... The neckband system was easy to use. Conclusions and Clinical Importance: Brachycephaly is associated with SDB. The neckband system is a feasible way of characterizing SDB in dogs.

 The epidemiology of upper respiratory tract disorders in a population of insured Swedish dogs (2011–2014), and its association to brachycephaly. M. Dimopoulou, K. Engdah, J. Ladlow, G. Andersson, Å. Hedhammar, E. Skiöldebrand, I. Ljungvall. Nature Sci. Repts. May 2023; doi: 10.1038/s41598-023-35466-0. Quote: Upper respiratory tract (URT) disorders are common in dogs but neither general nor breed-related epidemiological data are widely reported. This study´s aims were to describe the epidemiology of URT disorders in a Swedish population of dogs and to investigate whether brachycephalic breeds were overrepresented among high-risk breeds. A cohort of dogs insured by Agria Djurförsäkring in Sweden (2011–2014) was used to calculate overall and breed-specific incidence rate (IR), age at first URT diagnosis and relative risk (RR) for URT disorders. For breeds with high RR for URT disorders, co-morbidities throughout the dog’s insurance period and age at death were investigated. The cohort included approximately 450,000 dogs. URT disorders had an overall IR of 50.56 (95% CI; 49.14–52.01) per 10,000 dog years at risk. Among 327 breeds, the English bulldog, Japanese chin, Pomeranian, Norwich terrier and pug had highest RR of URT disorders. ... The boxer, CKCS [cavalier King Charles spaniel], Chihuahua, French bulldog, pug and standard poodle had high risk for co-morbidity both prior and after the first URT claim. ... The Boston terrier, boxer, CKCS, English and French bulldog and pug are brachycephalic breeds and affected to a variable degree by BOAS [brachycephalic obstructive airway syndrome]. ... The Chihuahua, CKCS, Pomeranian and Yorkshire terrier are breeds frequently affected with the URT disorder tracheal collapse. Although the brachycephalic breeds most often cited in association with URT disorders are the English and French bulldog, the pug and the Boston terrier, our study found that the Japanese chin, Pomeranian, CKCS and boxer also have an increased risk for URT disorders. Among 13 breeds with high RR for URT disorders in this study, eight (Boston terrier, boxer, CKCS, English bulldog, French bulldog, Japanese chin, Pomeranian, pug) are recognised as brachycephalic by most researchers. ... The brachycephalic conformation has been linked to an increased risk for URT disorders, and specifically BOAS, in the French and English bulldog, the CKCS, Boston terrier and the pug. ... Eight of 13 breeds with high RR for URT disorders were brachycephalic. The median age at first URT diagnosis was 6.00 years (interquartile range 2.59–9.78). French bulldogs with URT diagnoses had a significantly shorter life span (median = 3.61 years) than other breeds with URT diagnosis (median = 7.81 years). Dogs with high risk for URT disorders had more co-morbidities than average.

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2024

Evaluation of risk factors for sleep-disordered breathing in dogs. Iida Niinikoski, Sari-Leena Himanen, Mirja Tenhunen, Mimma Aromaa, Liisa Lilja-Maula, Minna M. Rajamäki. J. Vet. Intern. Med. February 2024; doi: 10.1111/jvim.17019. Quote: Background: Brachycephalic dogs display sleep-disordered breathing (SDB). The risk factors for SDB remain unknown. Objectives: To identify risk factors for SDB. We hypothesized that brachycephaly, increasing severity of brachycephalic obstructive airway syndrome (BOAS), excess weight, and aging predispose to SDB. Animals: Sixty-three privately owned pet dogs were prospectively recruited: 28 brachycephalic [including 8 cavalier King Charles spaniels (28.5%)] and 35 normocephalic (mesaticephalic or dolicocephalic) dogs. ... We had an overrepresentation of Cavalier King Charles Spaniels, French Bulldogs and Labrador Retrievers. Brachycephalic dogs were emphasized as SDB has been reported in these. ... Methods: Prospective observational cross-sectional study with convenience sampling. Recording with the neckband was done over 1 night at each dog's home. The primary outcome measure was the obstructive respiratory event index (OREI). Body condition score (BCS) was assessed, and BOAS severity was graded for brachycephalic dogs. Results: Brachycephaly was a significant risk factor for high OREI value (ratio of the geometric means 5.6, 95% confidence interval [CI] 3.2-9.9; P<.001) but aging was not (1.1, 95% CI 1.0-1.2; P=.2). Excess weight, defined as a BCS of over 5/9, (3.5, 95% CI 1.8-6.7; P<.001) was a significant risk factor. In brachycephalic dogs, BOAS-positive class (moderate or severe BOAS signs) was a significant risk factor (2.5, 95% CI 1.1-5.6; P=.03). ... Interestingly, Chiari malformation, a structural defect of the skull resulting in herniation of the brain into the spinal canal, has been associated with CSA in humans.52 Chiari-like malformation is prominent in many brachycephalic breeds, including the Cavalier King Charles Spaniel, where the defect is ubiquitous, but also in Pugs. However, central apnea or hypopnea events, excluding physiologic events related to sighs, did not occur in our study group. In a previous study, the resolution of apneas after extensive surgical procedures also supports obstructive, not central, apnea events in the Cavalier King Charles Spaniels studied. ... Although BOAS severity grading has not been evaluated in brachycephalic breeds excluding the extremely brachycephalic English Bulldog, French Bulldog and Pug, we performed it similarly in the other brachycephalic breeds. Only 1 of the 9 BOAS positive dogs represented a breed other than the 3 aforementioned breeds. This individual was a Cavalier King Charles Spaniel. It is possible that the BOAS severity grading used here does not accurately quantify the respiratory signs seen in other brachycephalic breeds. ... Conclusions and Clinical Importance: Brachycephaly decreases welfare in a multitude of ways, including disrupting sleep. Brachycephaly, increasing severity of BOAS and excess weight are risk factors for obstructive SDB.

Surgical management of brachycephalic obstructive airway syndrome: An update on options and outcomes. Mandy L. Wallace. Vet. Surg. July 2024; doi: 10.1111/vsu.14131. Quote: Dogs with a brachycephalic conformation often experience a collection of abnormalities related to their craniofacial conformation, which can lead to a variety of clinical signs such as stertor, exercise intolerance, respiratory distress, and gastrointestinal signs such as regurgitation, among others. This collection of abnormalities is termed brachycephalic obstructive airway syndrome (BOAS). With the rise in popularity of several brachycephalic breeds, veterinarians and veterinary surgery specialists are seeing these dogs with increasing frequency for surgical and medical treatment of these clinical signs, leading to an increased interest in developing surgical techniques for dogs with BOAS and evaluating objective methods of determining outcome after surgery. Advances in anesthetic management including standardized protocols and use of local nerve blocks to decrease opiate use may decrease postoperative complications. A variety of new or modified surgical techniques to manage hyperplastic soft palate and stenotic nares, among other BOAS components, have been developed and studied in recent years. Newer studies have also focused on risk factors for development of major complications in the postoperative period and on objective measurements that may help determine which patients will receive the most benefit from BOAS surgery. In this review, the newest studies focused on updates in anesthetic management, surgical techniques, and postoperative care will be discussed. Additionally, updated information on complication rates and outcomes for dogs undergoing surgical management of BOAS will be included.