"Do we really know if dog breeds used to be healthier than they are today?"
Even as I’m focusing my energy on creating my breeding project website, I still remain prone to writing lengthy comments in FB discussions about dog breeding. This is an adaptation and expansion of one of those comments. It’s obviously not an article with citations, but rather my thoughts on an interesting and frequently raised question. I thought I would share it for the sake of giving y'all some brain fodder to mull over and to provoke discussion.
A question that’s often raised in the discussion of genetic health in dogs is whether we definitively know that dogs today are more sickly than they once were.
This question is actually a red herring in the wider discussion of breeding and genetic health.
Since there’s no good data on the disease prevalence of the dog breeds of the past or measuring disease prevalence in breeds over a significant amount of time, it’s an unanswerable question. In many situations where this question is raised, the fact that we can’t definitively answer this question is actually the point of raising it. This is because it shifts the focus of the conversation to the presumed importance of monitoring disease prevalence in specific breeds instead of addressing the basic, undeniable fact that congenital disorders DO have a genetic basis and CAN be effectively prevented with proper breeding techniques.
It also suggests the possibility that purebred dogs are “supposed” to suffer from a certain level of genetic disease. This is, of course, an unfounded belief as we know that breeds of other animals exist without the alarmingly high rate of disease found in purebred dogs.
Further, it potentially suggests that the breeding techniques of yesteryear are something to be held up on a pedestal. The fact remains that the earliest dogs of our breeds may not have been more or less healthy because of the methods used by the breed founders but perhaps in spite of them. After all, the basic principles of dog breeding, such as the concept of blood purity and breeding only the best as a means of improving the breed, have remained largely unchanged in mainstream dog breeding culture to this day. Some of the specifics, like the implementation of genetic health and diversity testing, have changed, but the underlying principles are essentially the same as they were a century ago.
The truth is that the lack of data on the health of the dogs in the past is irrelevant as even today, there’s not really reliable data on the prevalence of health problems within particular breeds. Most of what we know is self-reported data from breeders in breed health surveys (hardly complete, certainly not randomly selected samples, and arguably biased) and a couple of datasets collected by veterinary hospitals (which only record the number of reported cases of diseases and do not evaluate what percentage of dogs within a breed have those diseases).
However, what we DO definitively know is that an increase in homozygosity, caused both by inbreeding and other factors like genetic drift, creates an increase of disease expression and a decrease of fertility, lifespan, and immune function. Most of the studies on this are done on livestock (Wright first formulated the COI in the early ‘20s based on livestock studies), but the principles are the same in dogs. There are a few studies in dogs which corroborate these findings, all of which are available on the ICB website.
Ultimately, I think too many breeders get caught up in trying to assess disease prevalence rather than simply applying known principles of genetics to guide their breeding practices. Once a genetic disorder becomes a noticeable problem, the gene pool is already going to be full of carriers, making those disorders impossible to “breed out” without reducing genetic diversity so much that another disease becomes a problem. This is what happened with Basenjis when breeders were overzealous about eliminating carriers for PRA from the gene pool, inadvertently causing Fanconi Syndrome to become a fixed trait and requiring an outcross to COO dogs to save the breed. With immune diseases, the problem is even worse, as immune health is founded in the diversity of DLA haplotypes rather than the absence of specific deleterious alleles. Once you lose enough of that diversity to cause immune disease, there’s no way to get it back without opening up the gene pool and widely disseminating the genes of many crossbred dogs to even out allele frequencies. No matter how much data you have on disease prevalence, it’s irrelevant as it does not facilitate the improvement of breed health in and of itself and typically comes only once it’s too late to utilize any simple solutions for the problems that have appeared.
Ideally, breeders SHOULD focus on crisis prevention and not damage control. Of course virtually no breeders do this and the way registries and clubs are currently run make it all but impossible for breeders to attempt it even if they wanted to. Closed studbooks, strict breed standards which often vary from country to country, and differing regulations on what can be registered as “purebred” are huge obstacles to restoring and protecting genetic diversity in dog breeds, which have effective population sizes so small that maintaining a closed gene pool forever is impossible.
For some breeders, there will NEVER be enough research or data to justify crossbreeding for improved health. This is a huge problem in Italian Greyhounds, which suffer from more immune diseases than any other breed. IG breeders continue to chant, “We need more studies before we change our breeding practices,” while the small window of ability to save the breed continues to close. Empirically proven methods for reducing the incidence of genetic diseases in animals are already well-studied and widely applied in other animal breeds and species, but they are intentionally ignored by the breeder community who insist that somehow, a vast body of breed-specific research is necessary to make smart breeding decisions. The truth is that nobody actually wants to change their traditional mindset and practices regardless of what modern science indicates. They simply want to find data to justify their presuppositions about breeding, and they will wait until hell freezes over to get it.
Lack of data is NOT the problem. Lack of scientific education, a refusal to apply all of what modern science has taught us about genetics rather than picking and choosing bits to support traditional practices, and an unrealistic determination to cling to outdated breeding principles as though they were quasi-religious truths transcending time and culture are the REAL roots of the problems our breeds face.