Epilepsy in Poodles
I was asked
some questions about the inheritance of epilepsy in standard poodles. These are
the questions:
1.) How
you know whether a particular poodle is a carrier?
2.) The difficult question of: Whether
the breeding program should be started all over again? Because the program
is based on the same line as the standard poodle that has epilepsy.
There is good reason to believe that epilepsy in poodles (all varieties) frequently is inherited. However, the mode(s) of inheritance are unknown. Thus, even in those cases where the epilepsy clearly is genetic, it is not possible to know whether both parents are carriers or only one parent is a carrier. Likewise, it is not possible to know how many (or which) of the litter mates are carriers or are likely to develop epilepsy themselves at a later point in time. These are the very questions that we are trying to answer in our long-term investigation of epilepsy in poodles. Unfortunately, epilepsy is extremely complex and it is likely to take us years before we have clear answers.
In many ways, it was the complexity and challenge of epilepsy that attracted me to work on this problem professionally. However, because of its complexity, a great deal of information is required to study it and to make breeding decisions. Most of the complexity is due to the fact that there is no positive diagnostic test for genetic epilepsy. In other words, there is no test that allows the veterinarian to say that your poodle tests "positive" for the disorder. The only way we can say with reasonable confidence that a poodle (or person) has inherited "primary" epilepsy (also called "idiopathic" epilepsy) is for the diagnostician to conduct numerous tests to examine the possibility that the seizures were due to factors *other than* primary epilepsy. There are *many* other factors that can cause seizures, including (but not limited to): exposure to poisons, head injury, infectious diseases, tumors, metabolic disorders. If the veterinarian finds no indication that the seizures were due to any of these other factors, then the dog is diagnosed as having primary epilepsy. We wrote a brief article in Poodle Variety (April-May, 1996, Handler's issue) that may help to further clarify this.
Veterinarians will differ in terms of which tests they recommend. The veterinary neurologist who is consulting on our research recommends the following for the initial evaluation:
1) Complete physical examination.
2) Neurological examination. On a general level, a neurological exam involves
testing the dog's reflexes for any signs of abnormal neurological functioning.
3) Complete blood count.
4) Serum Chemistry Profile.
5) Urinalysis.
6) Test of bile acids (fasting and 2-hour postprandial).
7) Tests for specific poisons to which the dog may have been exposed. For
example, you might suspect organophosphate poisoning if the dog had been exposed
to heavy levels of pesticides. You might suspect lead poisoning if you had been
doing remodeling that exposed old lead-based paints that the dog may have
chewed.
8) Importantly, you should provide the veterinarian with a detailed description
of the seizures, conditions under which the seizures occur, and a complete
medical history (including early diseases, prior injuries, vaccination history,
etc. This information can help to confirm or refute the diagnosis of primary
epilepsy.
9) Further tests may be recommended in cases of older dogs, for dogs who show
abnormal findings on any of the tests that are listed, and for dogs who show
severe seizures that do not respond to standard treatments (e.g., phenobarbital).
Further complexities are due to the possibility that there may be more than one kind of primary epilepsy. For example, in some lines, epilepsy may be a simple recessive disorder, but in other lines, epilepsy may be dominant or due to multiple genes.
Given our current lack of scientific knowledge, it is difficult to address the question of whether to start your breeding program over. As others have said, you need to weigh many issues. One issue is the seriousness of your poodle's seizures. The seriousness of primary (idiopathic) epilepsy varies greatly. Some dogs have very infrequent and mild seizures. Of those that have serious seizures, many respond well to standard anticonvulsant drugs. However, as I'm sure you know, many dogs do not respond to treatment, and their seizures are frightening and heartbreaking beyond words. Some of these are put down. What also would be helpful in making your decision (if you haven't done this already) would be to try tracking down whether there are other cases of epilepsy in the line (e.g., grandparents, aunts/uncles, half-siblings, cousins, as well as closer relatives) that may not have come to your attention thus far. Many pet owners do not contact the breeders to inform them of medical problems that may be genetic. There are numerous reasons for this. However, for many owners, it simply does not occur to them that this would be useful information for the breeder to know. As suggested, information about the incidence (how many other cases you find) and severity of the seizures in your poodle's line must be weighed against all the other positive traits in the line. I wish the decision were easier. The long-term goal of our research is to learn more about genetic and non genetic causes of seizures so these decisions will be easier in the future.
There is now a genetic (DNA test) for suspected carriers or affected dogs as well as others within the family who are not affected. At present it is only for Dobermans, Labrador Retreivers and Dachshounds. Later, Poodles and other breeds which are believed to have the problem will be added. Information c/o Optigen July 2003