Genetic aspects of idiopathic epilepsy in Labrador retrievers.

A study was undertaken to define the mode of inheritance of idiopathic epilepsy in Labrador retrievers in Switzerland. Seven hundred and ninety-two pedigree certificates from a population of healthy and epileptic dogs from 11 generations were evaluated. Forty-four different families (giving a total of 55 epileptic dogs) were included. Most patients showed generalised grand mal seizures and the onset was within one to three years in 41 per cent. Males were no more affected than females and the gender ratio between epileptic and control animals was not significantly different (P > 0.05). Additionally, there was no difference in average total inbreeding coefficient between both sexes, or with respect to age of onset of seizures. The increased manifestation of seizures in some subpopulations and the repeated occurrence in different families of the same sires suggested that there was a genetic basis for the condition in the breed. Results of pedigree analyses and from use of the binomial test support the hypothesis of a polygenic, recessive mode of inheritance. However, only an objective test-mating programme is likely to define the exact mode of inheritance.