Aussie Genetics Fact Sheet:
by C.A. Sharp
Seizures can be caused by a variety of things--injury, as a secondary effect of other disease, or toxic exposure--as well as heredity. If you have a dog that has seizures, the first thing you need to do is establish why it is doing so.
With injury, other disease or toxic exposure, treatment of the primary condition will stop the seizures in most cases, though if the primary condition causes permanent brain damage they may persist. A thorough veterinary work-up should reveal the cause of the problem if something other than hereditary epilepsy is involved. With virtually all of the other causes (the most likely exception being a brain tumor) there will be signs that something is wrong in addition to the seizures.
If no cause is found, the seizures are classified as "idopathic epilepsy," which means they are of unknown cause, but this type of epilepsy is generally accepted as inherited. There is not a positive test for primary epilepsy at present, so it can be diagnosed only by ruling out all other reasonable possibilities. The Canine Epilepsy Network, headed by the University of Missouri, is trying to develop a DNA test for canine epilepsy. If you or someone you know has affected dogs and can provide DNA samples (via cheek swab) on those dogs, please contact them: Canine Epilepsy Network
Primary epilepsy cannot be cured and will not go away. Seizures will occur periodically for the life of the dog if untreated. They often get worse if not controlled by medication. Treatment is no guarantee that the dog will be fine from there on out. The drugs themselves have side effects and in some cases they become ineffective. Epilepsy can kill.
The mode of inheritance for epilepsy is unknown but clearly not dominant. Therefore, both parents of an affected dog contributed genes, though the contribution may be unequal. It is possible that our breed might have more than one form of inherited epilepsy.
No epileptic dog should be bred, nor should any first-step relatives (parents, offspring, full or half siblings). More distant relatives should be bred with great care to avoid other affected families. Inbreeding in epilepsy families should be avoided at all costs and even line-breeding should be discouraged. Selecting unrelated mates reduces the probability of producing this or any hereditary disease considerably.