Clinical description and mode of inheritance of idiopathic epilepsy in English Springer Spaniels

Objective-To determine clinical characteristics and mode of inheritance of idiopathic epilepsy (IE) in English Springer Spaniels. Design-Original study. Animals-45 dogs with IE and 74 siblings and their respective parents. Procedure-IE was diagnosed on the basis of age at the time of seizure onset and results of laboratory testing and neurologic examinations. Simple segregation analysis was performed with the Davie method. Results-Median age at the onset of seizures was 3 years; however, 9 (20%) dogs were between 5 and 6 years old at the time of the onset of seizures. Twenty-one dogs (47%) had generalized seizures, and 24 (53%) had focal onset seizures. Results of segregation analysis were consistent with partially penetrant autosomal recessive or polygenic inheritance. Simulated linkage indicated that there was a 58% chance of obtaining suggestive linkage with the available pedigrees. Conclusions and Clinical Relevance-Results of the present study suggest that in English Springer Spaniels, IE segregates in a manner that is consistent with partially penetrant autosomal recessive inheritance (ie, a single major locus with modifying genes) or polygenic inheritance. Given enough families with accurate phenotypic information and available DNA, it should be possible to use genetic linkage analysis to identify chromosomal segments containing the causative gene or genes.