Seizures, Breeders, and Owners
Subject: Epilepsy and breeders: Part 2; Causes of Seizures; Responsibility of Owners to Notify Breeders
Date: Fri, 26 Sep 1997 14:14:37 -0400
From: Barbara Licht
ANY health problem can have multiple causes. However, as others mentioned, seizures can be particularly frustrating to both owners and breeders because of the very large number of causes. Dogs (and humans) can have seizures because they have inherited certain gene(s) that predispose them to have seizures. However, seizures also may be due to a variety of metabolic disorders (for example, liver disease, hypoglycemia), infectious diseases that affect the brain, head injuries, exposure to certain pesticides and other toxins, degenerative diseases of the central nervous system, heart and respiratory problems, tumors, and more. Thus, when an individual begins having seizures, it does not necessarily mean that the dog (or human) has inherited epilepsy (also called primary or idiopathic epilepsy). Rather, their seizures may be due to some other factor.
What further complicates the picture is that sometimes the "cause" of the seizures happens long before the first seizure was observed. For example, sometimes a young puppy may have an infectious disease that never shows serious symptoms, but that might permanently injure the cells in the brain. However, the seizures may not begin to occur until the dog's brain has matured and reached adulthood. (The reasons why seizures often don't begin until young adulthood when the brain is more mature are not well understood.)
Even if the seizures ARE genetic, the picture still is a bit muddled. I'll briefly present 2 reasons why. At least I'll try to be brief. You know what researchers are like--they do not know how to be brief or simple. :-)
The first reason is because of the complexity of the genetics and the second reason is because many owners don't report genetic problems to their breeder
.First, the genetic mechanisms for primary (idiopathic) epilepsy are likely to be complex. It is too early in our research to know how complex they really are, but let me try to explain just how complex they might be. 1) It is possible that more than one gene is involved (polygenic). 2) The gene(s) involved in certain lines of Poodles may be different than the gene(s) involved in other lines of Poodles (genetic heterogeneity). 3) As many of you know, when problems are "recessive," the disorder will not emerge unless BOTH parents carry the genes, although neither parent may actually show the disorder. (Note: we do not yet know whether epilepsy in Poodles is recessive.) 4) All this complexity is increased by the possibility of "incomplete penetrance." Incomplete penetrance refers to when individuals who inherit the gene(s) for specific disorders never actually show the disorder. This may be because these individuals have inherited some OTHER genes that protect them or because their environments are particularly protective against this disorder.
The implication of this complexity is that it is VERY hard, even for careful breeders, to predict if members of a litter will develop epilepsy. Often when breeders say, "This is the first time I have heard of seizures in this line," that is indeed the truth. There may not have been seizures observed in the line previously due to the combination of incomplete penetrance, recessive nature of the disorder, and/or other complexities (e.g., polygenic, genetic heterogeneity).
A second reason why the picture is muddled for many genetic disorders, such as epilepsy, is that owners often do not inform the breeder when health problems occur in their dog.
Thus, when a breeder says that she or he has not HEARD of this problem in their line before, it may be true, even when seizures do indeed run in the line. In particular, this is true for problems that do not occur until the dog is an adult. Although primary epilepsy CAN begin in puppyhood, it more frequently does not begin until after one year of age, and the most common age is 2-3 years. Even when breeders specifically tell the puppy owners to stay in touch and let them know about any problems, owners often don't. I am NOT suggesting that these owners are irresponsible. In some cases, they simply don't want to complain. In other cases, they don't understand how helpful it is to keep the breeder informed. And, yes, some DO care and DO want to contact the breeder, but somehow never get around to it. We all do that at times. This important issue has been discussed previously on this list and is worthy of further discussion.In most cases, I think it is NOT appropriate to "blame" either the breeder for not following up more carefully or the other owners who never reported the seizures (or other problems) to the breeder. Rather, the system of communication that currently exists is fallible and needs some improvements. I fully believe that the majority of breeders and dog owners DO care deeply about the health of their dogs. What we need (and I include myself here) is more education and practical ways to make it easier for owners and breeders (and researchers) to communicate so that no one feels they are being attacked.
Feel free to contact me for further information on the Poodle Epilepsy Project.
Barbara
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Barbara G. Licht, Ph.D. Voice: (850) 644-6272
Department of Psychology EMAIL: blicht@psy.fsu.edu
Florida State University FAX: (850) 644-7739
Tallahassee, FL 32306-1051