CONNECT WITH US

• HOME
• OVERVIEW
• BREEDERS
• ABOUT US
• CONTACT US
• CARDIOLOGISTS
• NEUROLOGISTS
• HEALTH CLINICS
• BLOG
• BOOKS
• RESCUE

Veterinary Resources

Cephalometric Measurements and Determination of General Skull Type of Cavalier King Charles Spaniels.  M. J. Schmidt, A. C. Neumann, K. H. Amort, K. Failing, M. Kramer. Vet. Rad. & Ultra, 26 Apr 2011. Quote: The general skull morphology of the head of the Cavalier King Charles Spaniel (CKCS) was examined and compared with cephalometric indices of brachycephalic, mesaticephalic, and dolichocephalic heads. ... Although the CKCS has been derived from the brachycephalic King Charles Spaniel, the CKCS has not been confirmed to be a member of a specific morphologic group. The phenotype of the CKCS does not seem to be brachycephalic at first glance. Compared with most brachycephalic breeds, the CKCS has a nose that is straight and well developed and inferior prognathism is seldom seen. However, there are indications from skull morphology that the CKCS is indeed a brachycephalic breed. A miniscule or absent frontal sinus and ventral orientation of the olfactory bulbs, both features of brachycephalic conformation, are present in the CKCS. Our purpose was to determine the general skull type of the CKCS based on classic cephalometric measurements and to validate the classic measurements against dogs with other skull types. ... Measurements were taken from computed tomography images. Defined landmarks for linear measurements of were identified using three-dimensional (3D) models. The calculated parameters of the CKCS were different from all parameters of mesaticephalic dogs but were the same as parameters from brachycephalic dogs. However, the CKCS had a wider braincase in relation to length than in other brachycephalic breeds. ... Brachycephalic traits include a shortened face, a rostrally elevated palate, an arched zygomatic apophysis, forward facing eyes, maxillary hypogenesis, aberrant conchal growth, dorsally rotated teeth, and breathing problems. Brachycephaly, however, also involves structural alteration of the neurocranium. The braincase is shortened and widened in brachycephalic dogs. Premature fusion of cranial base sutures is hypothesized to be the primary cause for the changes in skull morphology that lead to a reduction of the longitudinal axis of the cranial base.18,23,24 However, the force of the developing brain extends the skull along the lines of least resistance, laterolaterally, leading to a skull with increased width. This is reflected by the high cranial index of brachycephalic dogs in comparison to mesaticephalic dogs. ... Morphologic parameters of the head of the CKCS clearly differs from the mesaticephalic head type and the CKCS must be regarded as brachycephalic. In fact, the higher CI and LB3 in combination indicate an even shorter longitudinal axis of the neurocranium in comparison to the other brachycephalic dogs in our study. This must be considered when comparing specific features of the CKCS skull that may cause the deviation of the cerebellum into the foramen magnum or other morphologic changes. ... Studies of the etiology of the chiari-like malformation in the CKCS should therefore focus on brachycephalic control groups. As Chari-like malformation has only been reported in brachycephalic breeds, its etiology could be associated with a higher grade of brachycephaly, meaning a shorter longitudinal extension of the skull. This has been suggested for other breeds.

Volume reduction of the jugular foramina in Cavalier King Charles Spaniels with syringomyelia. Martin Jürgen Schmidt, NeleOndreka1,Maren Sauerbrey, Holger Andreas Volk, Christoph Rummel, Martin Kramer. BMC Veterinary Research. September 2012; doi: 10.1186/1746-6148-8-158. Quote: Background: Understanding the pathogenesis of the chiari-like malformation in the Cavalier King Charles Spaniel (CKCS) is incomplete, and current hypotheses do not fully explain the development of syringomyelia (SM) in the spinal cords of affected dogs. This study investigates an unconventional pathogenetic theory for the development of cerebrospinal fluid (CSF) pressure waves in the subarachnoid space in CKCS with SM, by analogy with human diseases. In children with achondroplasia the shortening of the skull base can lead to a narrowing of the jugular foramina (JF) between the cranial base synchondroses. This in turn has been reported to cause a congestion of the major venous outflow tracts of the skull and consequently to an increase in the intracranial pressure (ICP). Amongst brachycephalic dog breeds the CKCS has been identified as having an extremely short and wide braincase. ... Recently the CKCS has been shown to have an extremely high braincase length-width ratio (cranial index) compared to other brachycephalic dogs. ... A stenosis of the JF and a consequential vascular compromise in this opening could contribute to venous hypertension, raising ICP and causing CSF jets in the spinal subarachnoid space of the CKCS. In this study, JF volumes in CKCSs with and without SM were compared to assess a possible role of this pathologic mechanism in the development of SM in this breed. Results: Computed tomography (CT) scans of 40 CKCSs > 4 years of age were used to create three-dimensional (3D) models of the skull and the JF. Weight matched groups (7–10 kg) of 20 CKCSs with SM and 20 CKCSs without SM were compared. CKCSs without SM presented significantly larger JF -volumes (median left JF: 0.0633 cm3; median right JF: 0.0703 cm3; p < 0.0001) when compared with CKCSs with SM (median left JF: 0.0382 cm3; median right JF: 0.0434 cm3; p < 0.0001). There was no significant difference between the left and right JF within each group. Bland-Altman analysis revealed excellent reproducibility of all volume measurements. Conclusion: A stenosis of the JF and consecutive venous congestion may explain the aetiology of CSF pressure waves in the subarachnoid space, independent of cerebellar herniation, as an additional pathogenetic factor for the development of SM in this breed.

Comparison of Closure Times for Cranial Base Synchondroses in Mesaticephalic, Brachycephalic, and Cavalier King Charles Spaniel Dogs. Martin J. Schmidt, Holger Volk, Melanie Klingler, Klaus Failing, Martin Kramer, Nele Ondreka. Vet.Radiology & Ultrasound. Sept. 2013;54(5):497-503. Quote: premature closure of cranial base synchondroses has been proposed as the mechanism for brachycephaly in dogs and caudal occipital malformation syndrome (COMS) in Cavalier King Charles Spaniels. The purpose of this retrospective study was to compare times of closure for cranial base synchondroses in mesaticephalic, brachycephalic, and Cavalier King Charles Spaniel dogs. ... The Cavalier King Charles Spaniel has been recognized to be more brachycephalic than other brachycephalic dog breeds. ... Cranial magnetic resonance imaging studies were retrieved for client-owned dogs less than 18 months of age. Breed, age, skull conformation, and the open or closed state of cranial base synchondroses were independently recorded by two observers. For dogs with a unanimous observer agreement, regression analysis was used to test effects of age and gender on the open or closed status of synchondroses and differences between groups. A total of 174 dogs were included in MRI interpretations and 165 dogs were included in the regression analysis. Statistically significant differences in closure time of the spheno-occipital synchondrosis were identified between brachycephalic and mesaticephalic dogs (P = 0.016), Cavalier King Charles Spaniels and mesaticephalic dogs (P < 0.0001), and Cavalier King Charles Spaniels and brachycephalic dogs (P = 0.014). Findings from the current study supported the theory that morphological changes leading to the skull phenotype of the Cavalier King Charles Spaniels could be due to an earlier closure of the spheno-occipital synchondrosis.

Syringomyelia: determining risk and protective factors in the conformation of the Cavalier King Charles Spaniel dog. Thomas J. Mitchell, Susan P. Knowler, Henny van den Berg, Jane Sykes, Clare Rusbridge. Canine Genetics & Epidemiology. July 2014. Quote: Syringomyelia (SM) is a painful condition, more common in toy breeds, including the Cavalier King Charles Spaniel (CKCS), than other breeds. In these toy breeds, SM is usually secondary to a specific malformation of the skull (called Chiari-like Malformation, CM for short). ... The Cavalier King Charles Spaniel (CKCS) is a toy breed dog, popular as a companion and also in the conform- ation showing fancy with 5,970 and 39,670 new registra- tions in 2012 with the Kennel Club (KC) and worldwide respectively [1]. The CKCS, like many brachycephalic toy breeds, is predisposed to syringomyelia, a condition where fluid filled cavities (syrinxes) develop within the central spinal cord.  ,,, There has been debate as to whether head shape is related to CM/SM, especially as some humans have similar characteristic facial and skull shapes, and what this may be. Identifying a head shape in dogs that is associated with these diseases would allow for selection away from these conditions and could be used to further breeding guidelines. 133 dogs were measured in several countries using a standardised 'bony landmark' measuring system and photo analysis by trained researchers. This paper describes two significant risk factors associated with CM/SM in the skull shape of the CKCS: extent of brachycephaly (the broadness of the cranium (top of skull) relative to its length) and distribution of doming of the cranium. The study showed that having a decreased cephalic index (less brachycephaly) was significantly protective. Further to this, more cranium at the back of the head (caudally) relative to the amount at the fro nt of the head (rostrally) was significantly protective against disease development. This was shown at three and five years of age, and also when comparing a sample of “SM clear” individuals over five years to those affected under three years. This study suggests that brachycephaly, with resulting rostrocaudal doming, is associated with CM/SM. These results could provide a way for selection against the risk head shape in the CKCS, and thus enable a reduction in CM/SM incidence. Studying other breeds in which CM free individuals are more frequent may validate this risk phenotype for CM too.

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. ... Although the CKCS is recognised as having a brachycephalic skull [40], facial length is very varied in the breed, with the muzzle becoming fashionably shorter and more dorsally rotated (airorhynchy) in the last decade  ... 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.

Computed tomographic morphometry of tympanic bulla shape and position in brachycephalic and mesaticephalic dog breeds. Ben Mielke, Richard Lam, Gert Ter Haar. Vet. Rad. & Ultra. July 2017. Quote: Anatomic variations in skull morphology have been previously described for brachycephalic dogs; however there is little published information on interbreed variations in tympanic bulla morphology. This retrospective observational study aimed to (1) provide detailed descriptions of the computed tomographic (CT) morphology of tympanic bullae in a sample of dogs representing four brachycephalic breeds (Pugs, French Bulldogs, English Bulldog, and Cavalier King Charles Spaniels) versus two mesaticephalic breeds (Labrador retrievers and Jack Russell Terriers); and (2) test associations between tympanic bulla morphology and presence of middle ear effusion. Archived head CT scans for the above dog breeds were retrieved and a single observer measured tympanic bulla shape (width:height ratio), wall thickness, position relative to the temporomandibular joint, and relative volume (volume:body weight ratio). A total of 127 dogs were sampled [including 25 cavaliers]. Cavalier King Charles Spaniels had significantly flatter tympanic bullae (greater width:height ratios) versus Pugs, English Bulldogs, Labrador retrievers, and Jack Russell terriers. French Bulldogs and Pugs had significantly more overlap between tympanic bullae and temporomandibular joints versus other breeds. [See Figure 3 at right.] All brachycephalic breeds had significantly lower tympanic bulla volume:weight ratios versus Labrador retrievers. Soft tissue attenuating material (middle ear effusion) was present in the middle ear of 48/100 (48%) of brachycephalic breeds, but no significant association was found between tympanic bulla CT measurements and presence of this material. Findings indicated that there are significant interbreed variations in tympanic bulla morphology, however no significant relationship between tympanic bulla morphology and presence of middle ear effusion could be identified. ... Cavalier King Charles Spaniels represent a unique subset of brachycephalic animals as they were found to have significantly flatter tympanic bullae (defined by width: height ratios) than other brachycephalic breeds. There was a high percentage of Cavalier King Charles Spaniels with soft tissue attenuating material in the middle ear (68%), which may have falsely reduced the internal measurements obtained, increasing width: height ratio (internal) artifactually. However, given the fact that the lower bound of the 95% confidence interval measurements for Cavalier King Charles Spaniels (width:height ratio (internal) 1.47−1.65)) was greater than the upper bound for all breeds (except the French Bulldog which also had a high percentage of material in middle ear (80%)), authors believe it is likely that these measurements represented real changes present in this breed. Cavalier King Charles Spaniels have been described to have a unique disease resulting in the formation of a buildup of highly viscous mucus within the middle ear (primary secretory otitis media or otitis media with effusion) of dogs without clinical evidence of otitis externa. It is thought that, due to a lack of inflammation or signs of infection in the middle ear, the disease is due to auditory tube dysfunction based on possible anatomical changes of the middle ear or the auditory tube. The finding of an anatomical variation in the shape of the tympanic bulla of Cavalier King Charles Spaniels may offer a potential explanation for the pathogenesis of this disease in addition to the previously suggested changes in the orientation and function of the auditory tube. However, given the lack of histopathology and contrast-enhanced CT scan evaluations in the current study, this hypothesis is speculative. Further investigation to identify potential pathway alteration of the auditory tube in the Cavalier King Charles Spaniel would be an interesting addition for further clarification of this disease process.

A genome-wide association study identifies candidate loci associated to syringomyelia secondary to Chiari-like malformation in Cavalier King Charles Spaniels. Frédéric Ancot, Philippe Lemay, Susan P. Knowler, Karen Kennedy, Sandra Griffiths, Giunio Bruto Cherubini, Jane Sykes, Paul J. J. Mandigers, Guy A. Rouleau, Clare Rusbridge, Zoha Kiba. BMC Genetics. March 2018;19:16. Quote: Background: Syringomyelia (SM) is a common condition affecting brachycephalic toy breed dogs and is characterized by the development of fluid-filled cavities within the spinal cord. It is often concurrent with a complex developmental malformation of the skull and craniocervical vertebrae called Chiari-like malformation (CM) characterized by a conformational change and overcrowding of the brain and cervical spinal cord particularly at the craniocervical junction. CM and SM have a polygenic mode of inheritance with variable penetrance. ... In the CKCS, risk of SM has been shown to be associated with increased brachycephaly with rostrocaudal doming i.e. a heightened cranium that slopes caudally [8] and reduced skull base due to craniosynostosis or premature skull suture closure. ...   Results: We identified six cranial T1-weighted sagittal MRI measurements that were associated to maximum transverse diameter of the syrinx cavity. Increased syrinx transverse diameter has been correlated previously with increased likelihood of behavioral signs of pain. We next conducted a whole genome association study of these traits in 65 Cavalier King Charles Spaniel (CKCS) dogs (33 controls, 32 with extreme phenotypes). Two loci on CFA22 and CFA26 were found to be significantly associated to two traits associated with a reduced volume and altered orientation of the caudal cranial fossa. Their reconstructed haplotypes defined two associated regions that harbor only two genes: PCDH17 on CFA22 and ZWINT on CFA26. PCDH17 codes for a cell adhesion molecule expressed specifically in the brain and spinal cord. ZWINT plays a role in chromosome segregation and its expression is increased with the onset of neuropathic pain. Targeted genomic sequencing of these regions identified respectively 37 and 339 SNPs with significantly associated P values. Genotyping of tagSNPs selected from these 2 candidate loci in an extended cohort of 461 CKCS (187 unaffected, 274 SM affected) identified 2 SNPs on CFA22 that were significantly associated to SM strengthening the candidacy of this locus in SM development. Conclusions: We identified 2 loci on CFA22 and CFA26 that contained only 2 genes, PCDH17 and ZWINT, significantly associated to two traits associated with syrinx transverse diameter. The locus on CFA22 was significantly associated to SM secondary to CM in the CKCS dog breed strengthening its candidacy for this disease. This study will provide an entry point for identification of the genetic factors predisposing to this condition and its underlying pathogenic mechanisms.

Morphometric Analysis of Spinal Cord Termination in Cavalier King Charles spaniels. Courtney Sparks. ACVIM Forum, Abstract N-15. June 2018. Quote: Cavalier King Charles spaniels (CKCS) suffer from Chiari-like malformation (CM), a skull malformation that causes crowding of the caudal fossa, and syringomyelia (SM). Affected dogs show signs of pain and frequently show lumbosacral pain. Tethered cauda equina has been reported in people with CM but currently there is no morphometric data on the caudal aspect of the vertebral column and spinal cord in CKCS. The purpose of this study was to compare the location of the conus medullaris in CKCS with other size-matched breeds. We hypothesized that the spinal cord terminates more caudally in CKCS. A retrospective study was conducted on 90 dogs with thoracolumbar magnetic resonance imaging (MRI). Dog breeds were grouped as CKCS (n=48), and brachycephalic (n=21) and non-brachycephalic (n=20) size-matched controls. ... Cavalier King Charles Spaniels are classified as a brachycephalic breed and this classification is considered important in morphometric analyses of their skull and brain. ... MRI identifiers were removed to blind the observer. Termination of the spinal cord was determined from T2-weighted sagittal and axial images as the 6th (L6), or 7th lumbar vertebra (L7), or sacrum. Breed was revealed after Chi-squared analyses were performed. Among 48 CKCS, the spinal cord terminated at L6 in 3, L7 in 23, and sacrum in 22 dogs compared with 8 at L6, 27 at L7 and 5 at sacrum in 41 controls. Spinal cord termination was significantly more caudal in CKCS as compared to brachycephalic (P = 0.015) and non-brachycephalic breeds (P = 0.005). There was no difference between size-matched controls (P = 0.157). There is a need to investigate whether tethering of the cauda equina contributes to signs of pain in CKCS.

RETURN TO TOP