164 – Busting the Genetic Testing Myths: Dr. Jerold Bell
BUSTING THE GENETICS MYTHS: DR JEROLD BELL
Last week we talked with Dr. Marty Greer about health testing 101. This week we’re taking the graduate course in genetics with Dr. Jerold Bell from Tufts University’s Cummings School of Veterinary Medicine.
Bell has some serious myth busting going on in this discussion that I think our listeners are going to enjoy.
MIXED BREEDS ARE NOT HEALTHIER
First of all, mixed breeds are not healthier than purebred dogs.
“The most frequent genetic disorders that we see in practice are seen equally between purebreds and mixed breeds,” Bell said.
Second, there is a heritability factor in many diseases we had not previously considered. Bell talks specifically about studiesindicating even something as seemingly obviously traumatic as cruciate ligament tears have a genetic component.
Third, all breeders should be health testing their dogs. The increasing number of DNA tests available enables breeds with simple recessive gene pairs creating disease to quickly and easily apply positive pressure to the pedigree. Breeding a quality carrier status animal to a clear, then breeding the resulting quality clear offspring, Bell said, will rapidly eliminate diseases such as a specific form of Progressive Retinal Atrophy.
“And that’s really the take home message for today,” Bell said. “Is that anyone that’s doing breeding must be doing breed specific genetic testing of the parents and if they’re not doing that then they should not be breeding. Then they are not an ethical breeder and not a health conscious breeder and there’s no place today for breeders that are not going to do that.”
Fourth, for complex inherited diseases, in which a combination of genes is causing a disease process to be expressed, the OFA/CHIC database offers the opportunity to research a “vertical pedigree” to study the incidence of disease in the entire family of the dogs being considered for breeding.
OFA IS FACEBOOK FOR DOGS
“So when you look up at dog’s web page on the OFA Website,” Bell said, “and this is Facebook for dogs, this is the dog’s own individual website. They can have their picture on there, it has all their information. It has all the information of the tests results from the parents from the siblings from the half siblings. … even in a normal individual that you’re looking at for breeding, if the parents or the parents’ siblings (indicate) more disease present, it tells you that you’re going to have a greater genetic load of liability genes for that particular disorder.”
Finally, using health testing *appropriately* is mission-critical. Bell noted that breeders’ selection processes should emphasize only those diseases which are of concern within their respective breeds. He presented an outstanding webinar for the AKC Canine Health Foundation available here which goes into even greater detail on this topic.
“…people might say that because (our dogs) purebred they have limited diversity and therefore they’re unhealthy,” Bell said. “And that is not true.’
We hope you enjoy this very rich conversation with Dr. Bell and are able to apply this knowledge in your own breeding programs.
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Having read much of Jerold Bells work it is refreshing to see his opinion has not faulted from using pedigree analysis in conjunction with Breed specific health tests being the best approach in making the best puppies.
If breeders over analyse , over test and understand very little of the dogs in the background of any pedigree they will throw the baby out with the bath water and lose structure conformity and type within as little as 3 generations and in some breeds this is already showing like Havanese. Applying draconian methods of eugenics will for sure kill off what drew these people to the breed in first place. Breeders are not god and should before it is too late stop thinking they are! Nature needs s hand not an axe!