A cohort study of epilepsy among 665,000 insured dogs: incidence, mortality and survival after diagnosis.

The main objective of this study was to estimate the incidence and mortality rates of epilepsy in a large population of insured dogs and to evaluate the importance of a variety of risk factors. Survival time after a diagnosis of epilepsy was also investigated. The Swedish animal insurance database used in this study has previously been helpful in canine epidemiological investigations. More than 2,000,000 dog-years at-risk (DYAR) were available in the insurance database. In total, 5013 dogs had at least one veterinary care claim for epilepsy, and 2327 dogs were euthanased or died because of epilepsy. Based on veterinary care claims the incidence rate of epilepsy (including both idiopathic and symptomatic cases) was estimated to be 18 per 10,000 DYAR. Dogs were followed up until they were 10 (for life insurance claims) or 12 years of age (veterinary care claims). Among the 35 most common breeds in Sweden, the Boxer was at the highest risk of epilepsy with 60.3 cases per 10,000 DYAR, and also had the highest mortality rate of 46.7 per 10,000 DYAR (based on life insurance claims). Overall, males were at a higher risk than females (1.4:1). Median survival time (including euthanasia and death) after diagnosis was 1.5 years. In general, breeds kept solely for companionship lived longer after diagnosis than those kept for dual-purposes, such as hunting and shepherd and working breeds. The study demonstrates marked breed differences in incidence and mortality rates, which are assumed to reflect genetic predisposition to epilepsy.