Disease Progression and Treatment Response of Idiopathic Epilepsy in A ustralian S hepherd Dogs

Background Idiopathic epilepsy ( IE ) in Australian Shepherds ( AS s) occurs worldwide but there is a lack of description of the epilepsy syndrome in this breed. The ABCB 1‐1Δ mutation is more prevalent in AS s than in many other dog breeds. Hypothesis Australian Shepherds suffer from a poorly controlled IE syndrome with prevailing severe courses. Seizure control and ABCB 1‐1Δ mutation might be related in this breed. Animals Fifty ASs diagnosed with IE and 50 unaffected ASs. Methods Predominant study design is a longitudinal cohort study. Pedigrees, medical records, seizure, and treatment data of AS s with IE were analyzed descriptively. Sex, color, and the ABCB 1‐1Δ genotype were compared between case and control groups and AS s with poorly or well‐controlled seizures. Differences in survival times were assessed by logrank tests and C ox regression analysis. Results Idiopathic epilepsy in AS s is dominated by moderate and severe clinical courses with the occurrence of cluster seizures and status epilepticus and a high seizure frequency. Poor seizure control and a high initial seizure frequency (≥10 seizure days/first 6 months) are associated with shorter survival times ( P  < .05). Poor seizure control, unrelated to the ABCB 1( MDR 1) genotype, is evident in 56% of epileptic AS s. Pedigree analysis suggests a genetic basis. Conclusion and Clinical Importance Frequent severe clinical courses, poor seizure control unrelated to the ABCB 1( MDR 1) genotype, and a young age at death compromise animal welfare and warrant further genetic studies to unravel the underlaying molecular mechanisms of IE and seizure control in the breed.