Abstract
Chiari-like malformation (CM), syringomyelia (SM) and middle ear effusion (also called PSOM) are three conditions that frequently occur in Cavalier King Charles Spaniels (CKCS). Both CM and SM are currently screened in the Netherlands prior to breeding and are graded according to the British Veterinary Association’s Kennel Club (BVA/KC) scheme. This study evaluated the prevalence and estimated genetic parameter of CM, SM and middle ear effusion from 12 years of screening results. For SM, the classical method using the BVA/KC scheme, was compared with exact measuring of the central canal dilation. For CM, the BVA/KC scheme was compared with a more detailed scheme. Next to this the presence of microchip artifacts was assessed. 1249 screening of 1020 dogs were re-evaluated. Results indicated the presence of CM in all dogs, suggesting it has become a breed-specific characteristic. And although different grades of CM were observed, the condition did not deteriorate over time. SM was present in 39% of the dogs and a clear age effect was demonstrated, with SM increasing with age. This emphasizes the importance of screening at appropriate age, since SM can worsen with increasing age. One alternative is to promote repeated measures. The presence of middle ear effusion in this study was 19%–21% for dogs younger than 3 years, and 32%–38% for dogs older than 3 years. In as much as 60%, microchip artifacts were noticed, leading to the recommendation to place microchips in another location in breeds that are susceptible to developing SM. Finally, this study estimated the heritability of CM in this population, due to the lack of phenotypic variance, to be very low at 0.02–0.03. The heritability for SM central canal dilatation to be 0.30, compared to 0.13 for the classical BVA/KC method, using a model including the age effect and the combined effect of veterinary clinic and year of the evaluation. Genetic correlations were rather small, ranging from 0.16–0.33. As a conclusion, screening for SM and CM in the entire population should be maintained, and a selection scheme against SM should be based on estimated breeding values for the exact measurement of the central canal dilatation.
Highlights
Chiari malformation (CM) is the herniation of the cerebellum through the foramen magnum [1]
In the Cavalier King Charles Spaniel (CKCS) it has been described as a Chiari-like malformation as it is a combination of two causes: an abnormally small caudal cranial fossa [2], and increased cerebellar volume [3], and is diagnosed using magnetic resonance imaging (MRI) scans
Diagnosis is made by magnetic resonance imaging (MRI) of the spinal cord, where the central canal dilation (CCD) or presence of a syrinx, is assessed
Summary
Chiari malformation (CM) is the herniation of the cerebellum through the foramen magnum [1]. CM is often referred to as the cause of syringomyelia (SM), recent work has proven that there is a relation between the two disorders but one cannot conclude its causality [2,5]. Both CM as well as SM have been found to be endemic in the CKCS [6]. SM can present itself as a dilation of the central canal or as fluid-containing cavities or syrinxes within the spinal cord. About 35% of the dogs having SM display the clinical signs associated with the disease [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
