Prevalence of structural and idiopathic epilepsy in brachycephalic and non-brachycephalic dogs in the context of the International Veterinary Epilepsy Task Force guidelines.

Abstract

OBJECTIVES: To report the relative prevalence of structural and idiopathic epilepsy in brachycephalic and non-brachycephalic breeds in the context of the International Veterinary Epilepsy Task Force guidelines. A secondary objective was to compare the age at diagnosis of structural epilepsy in brachycephalic and non-brachycephalic dogs. MATERIALS AND METHODS: Medical records were reviewed retrospectively for dogs presenting to a single centre for investigation of generalised seizures. Patients were categorised based upon skull conformation, age, interictal neurological examination and the presence of structural lesions identified on magnetic resonance imaging that were deemed likely to cause seizures. Descriptive statistics, the Mann-Whitney U test and Bayesian analysis of the data were performed to investigate the associations between skull conformation, the presence of structural lesions and the age of onset of structural epilepsy. RESULTS: A structural lesion was identified as the probable cause of seizures in 34.2% (38/111) of dogs. 61.8% of brachycephalic dogs had a structural lesion compared to 22.1% of non-brachycephalic dogs. 33.3% of brachycephalic dogs aged 6 months to 6 years with a normal interictal neurological examination were diagnosed with a structural lesion compared to 0% of non-brachycephalic dogs in this age category. The median age at diagnosis of structural epilepsy in brachycephalic dogs (60 months) differed significantly from that of non-brachycephalic dogs (108 months). CLINICAL SIGNIFICANCE: Brachycephaly was identified as a risk factor for structural epilepsy in this study population, suggesting that magnetic resonance imaging of the brain and cerebrospinal fluid analysis should be more strongly considered in brachycephalic dogs who otherwise satisfy a tier I confidence level diagnosis of idiopathic epilepsy, independent of the interictal neurological examination.