Idiopathic epilepsy affects nearly 30 different dog breeds and in a 1999 survey is considered one of the top canine health issues identified by the AKC Parent Clubs. Preliminary studies in the Belgian Tervuren indicates that although this is a heritable disorder governed by many genes, there exists a single gene of very large effect on the incidence of epilepsy. The epileptic condition influenced by this particular gene is inherited as an autosomal recessive. The specific objective of the project is to develop a genetic marker associated with that locus in the Belgian Tervuren by utilizing the emerging canine genetic map. Such a genetic marker will permit the identification of carriers of epilepsy in Belgian Tervuren, and possible other breeds as well, with the end result that breeders can make informed health-based breeding decision.