Determining whether or not a dog should be used for breeding is not always easy, which is just one of the reasons why I cringe when I hear pet owners say that they want to breed their dog "for the experience," or "to have one of his or her offspring."
Responsible breeders put a lot of money and effort towards making sure that only the healthiest individuals pass their genes on to the next generation.
One way breeders can do this is via genetic testing. Many of the diseases that most frequently affect purebred dogs have a genetic component, meaning that at least in part, a dog’s DNA determines whether or not he or she develops the disease in question. When the inheritance pattern for the disease is relatively straightforward (i.e., a single gene is responsible and it is passed on in a simple dominant/recessive pattern), DNA testing can mean the difference between a litter of healthy pups and a nightmare of medical consequences.
DNA testing is powerful. It can be performed at any age, which reduces the chance that a problem will be detected after litters have already been produced. It also provides fairly definitive results, resulting in fewer judgment calls that can allow "bad" genes to remain in the population. No test is infallible however, so always analyze the results in combination with all the information that you have available.
Unfortunately, the inheritance of some canine diseases is very complicated, which means that DNA testing is not feasible, at least for the time being. When multiple genes are involved or environmental factors play a large role in disease expression, looking at the dog’s body (e.g., phenotypic testing via exams, blood work, X-rays, etc.) is the best option we have available. This is a less than perfect situation, because individuals may not have symptoms themselves but can still pass on abnormal genes to their offspring, or they may not have a detectable disease until later in life, after they have already been bred.
To learn about all of the different types of tests that are available, check out these resources:
- The Orthopedic Foundation for Animals provides a listing of "currently available DNA tests"
- The Canine Health Information Center lists breeds that are enrolled in the CHIC program and include associated lists of recommended genetic and phenotypic tests for each breed
If you are considering purchasing a purebred dog, go to these sites, search for the type of dog you are interested in, and then ask breeders for their results. If they look at you with blank expressions or try to evade your questions, move on to a different breeder. Owners can also use these websites to learn about some of the diseases that their pets might be predisposed to. Talk to your veterinarians to determine whether or not testing might provide you with useful information.
Dr. Jennifer Coates