Health Clearances: Essential or Irrelevant?
Some breeders have questioned the efficacy of health testing, as well as its relevancy when not everyone in a breed does the tests.
Susi Szeremy |
September 5, 2013
A simple DNA test like this can reveal if a dog is a carrier of many diseases, but limiting reproduction to only those dogs testing clear for disease may result in a breed robust with health but also one that lacks breed type. Photo by Susi Szeremy.
Whiskey didn't have a particularly good life, most of it having been spent going nowhere in an oversized hamster wheel. He'd been bred for the sole purpose of powering pulleys that would turn a rotisserie in a nearby fireplace. Although it would be another 200 years before architect Louis Sullivan would advocate "form following function," Whiskey was evidence that breeders were already creating purpose-bred dogs. Unconcerned about appearances, they cared only that their "turnspit dogs" be short-legged to fit inside a wheel and long-bodied to turn more of it at a time. Now stuffed and on display at the Abergavenny Museum in the UK, poor Whiskey is the last surviving specimen of a breed that eventually died out, its closest descendant the Glen of Imaal Terrier.
Today's breeders, conversely, have been criticized for sacrificing a dog's ability to function in favor of placing too much emphasis on a breed's appearance. They stand accused of looking past their dog's health by creating exaggerated caricatures of breed standards in pursuit of ribbons and rosettes. This viewpoint, roundly embraced by animal rights proponents, is problematic for me. Certainly there are breeders who have lost sight of the importance of breeding for type and soundness (if they ever had it to begin with), but substandard breeders are no more representative of the dog fancy than a Barbie doll is of an average woman's appearance.
Truly ethical breeders have always placed a premium on breeding a dog sound enough to do the job it was bred to do even as they maintain type. Many old-time breeders started testing their dogs with what was available to them long before it became de rigueur, and there was a time when the breeder who performed OFA, BAER and CERF tests on his or her dogs was as thorough as anyone could be. Since 2005, however, testing options have exploded with the completion of canine genome mapping, and some 500 hereditary disorders have been described that affect both purebred and mixed breeds. As of 2012, markers for more than 100 diseases have been mapped to mutations in particular genes, with more mutations being discovered exponentially. Currently, a simple cheek swab can identify a dog as clear, afflicted or a carrier of many diseases, and breed clubs are increasingly encouraging, if not requiring, breeders to include more comprehensive testing in their breeding programs.
This is an exciting development if a breeder has 2.5 billion bases divided among 20,000 genes and 39 chromosomes (the number in the canine genome) with which to play, but because dogs have been genetically divided into breeds developed from a few original individuals, each breed has a much smaller set of "mischievous" genes — sometimes only one or two — that underlie a disease. In reality, breeders of purebred dogs have to work with a considerably smaller gene pool, and the genetic "paint box" of rare-dog breeders is downright limited. As Robert Wayne, a biologist at UCLA, said, "The story that is emerging [from the genome project] is that the diversity in domestic dogs derives from a small genetic tool kit."
Questions and Dilemmas
With these narrow parameters, some breeders have questioned the efficacy of health testing, as well as its relevancy when not everyone in a breed does the tests. Given human nature in a competitive sport, a few fanciers have even wondered about the wisdom of disclosing the results of health tests done on their dogs. The conversation provokes questions and poses dilemmas:
+ Dr. Greg Keller of the Orthopedic Foundation for Animals concedes that statistical proof of progress toward a disease's eradication can be skewed when only positive results are reported. Currently, most test results are made public at the discretion of a dog's owner, but not everyone is inclined to share unfavorable results. If publishing all results were made mandatory, however, might fewer people breed their dogs rather than submit themselves to the scrutiny of their peers — and if so, is this a bad thing?
+ Dr. Keller added that while it's possible to show the positive impact of hip and elbow dysplasia testing because of 30 years' worth of results, at present it's impossible to chart the impact of DNA tests because it's simply too soon in the evolution of testing. Could it be that we are "throwing the baby out with the bathwater" because we are depending on results of genetic tests so soon after they were developed? To paraphrase what one breeder lamented, what a shame that some beautiful dogs were pulled and spayed/neutered over the years because of one test in their breed that advances in science ultimately determined as inconclusive.
+ Is a breed club being a good steward of its breed, or untenably intrusive, by strongly recommending, if not requiring, that any dog used for breeding be DNA tested, and that noncompliance could result in a breeder being excluded from holding office or serving on committees? Is it fair or even helpful to coerce honest breeders into paying the high cost of DNA fees to prove their integrity?
+ Should health testing be a condition of AKC registration?
+ While DNA findings are conclusive, the reading of other test results can be subjective, particularly in digital X-rays where resolution can impact the quality of the X-ray. How many of us have shared X-rays with a potential stud dog owner or co-breeder and made breeding decisions influenced by the interpretations of a layman?
+ How many dogs have been eliminated from a gene pool as a result of a test but never developed the disease as an older dog?
+ At a time whn the fancy is hemorrhaging membership numbers, would mandatory publication of test results discourage owners from getting involved in the dog fancy if their dog is revealed as a known carrier, even if they have no intention of breeding it?
+ And finally, is testing positive for a disease reason enough to eliminate a dog from a gene pool?
To answer these questions for myself, I fall back on something I learned as a newbie from experienced horsemen and dog people: the importance of balance. Limiting reproduction to only those dogs testing clear for disease may result in a breed robust with health but also one that lacks breed type. Breeding untested dogs, however, no matter how vigorous they appear, has a profound impact on a breed's gene pool. To think otherwise is as foolish as believing that a drop of red ink won't impact a cup of white paint. Breeding for phenotype (the qualities we see) is important, but breeding for what we don't see (genotype) is no less so. The good news is that with time, patience, a rational breeding plan and the commitment to make tough choices, collaborating with science just might enable us to have it all one day: Breed type and a gene pool free of malady.
When asked during an informal poll if testing is essential or irrelevant, experienced breeders concurred that testing is an essential tool. But it is irrelevant if the results are ignored, withheld, done on a limited number of dogs or used unwisely in a breeding program, especially in rare breeds.
As a couple of veterinarian-breeders told me, even affected dogs with otherwise highly desirable traits should be considered in a breeding program, but only with dogs that have tested completely clear. Resulting puppies would likely be carriers never affected, and they, in turn, can be bred to all-clear dogs or very selectively to other carriers. The bottom line is that fanciers need to look at the whole dog, not just test results, and use with judgment and discretion those test results to advance the future of breeds free of genetic disease and maintain dogs with breed type.
Attitudes About Testing
A few "attitude adjustments" would hasten this process. As unlikely as it is to happen, animal rights proponents need to reassess the wisdom of their vilification of breeders and acknowledge that the vast majority of research into canine health is funded by AKC breed clubs. Attitudes of some in the dog fancy need to change, as well. Ours is a competitive environment, but on the subject of dog health, it would be helpful to embrace the reality that we're all in this together and that ownership of an afflicted dog in a breeding program does not make one a pariah. As one old-time breeder told me, "Honey, if you've never encountered an issue in your dogs, you just haven't been in the breed long enough."
There will always be those breeders who see DNA tests as useless because so few dogs in their breed become symptomatic. As that old-time breeder suggested, however, it's only a matter of time. To that end, clubs need to continue to educate, educate, educate.
A few years ago at my own breed's national specialty, I was among a room full of stunned owners and breeders sitting in the glow of an overhead projector as we absorbed the evidence that not only had DM (degenerative myelopathy) been found in our breed, but that a dog we all knew was suffering from it. His bereaved owner stood up and shared with us the nature of this progressive disease of the spinal cord that ultimately killed his beloved dog a few years later. I suspect I wasn't the only person to return home from that specialty and make it my first order of business to order a DNA kit for my own dogs. The realization that there are dogs at risk in my breed from a disease many of us hadn't heard of before that night is sobering, and it has forced some of us to look at breeding in a new light. It has forced us to consider "what if" scenarios in a highly personal way.
Breeding away from a genetic issue takes time, methodology and the concerted effort of a breeding community. In a perfect world, clubs would have frank discussions with their members about the diseases in their breed. The more open the dialogue, the less the stigma borne of ignorance.
Judicious use of health testing is an important tool for a breeder, to be sure, but as one breeder told me, "If we throw out every dog that doesn't pass all its health tests, then we will very rapidly make our breeds extinct. Whether we select for type or health will be moot; there won't be any dogs from which to select."
The answer, I believe, is balance.
From the August 2013 issue of Dogs in Review magazine. Purchase the August 2013 digital back issue or
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