Why talk about dogs?

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These two Dogue de Bordeaux have the extremely narrow, upright nostrils that are common in the breed. This and other anatomical exaggerations are why the Dogue is included in the Kennel Club list of high profile breeds subject to separate vet checks at shows. (Photos from Wikipedia.)

As I mentioned in the previous post, I want to do a series of posts on the subject of genetic diversity. Obviously the primary focus of this blog is horses, but for this particular topic I will be jumping back and forth a bit between the world of dogs and the world of horses. The situation in many purebred dog breeds is quite dire. With few exceptions, horse breeds do not face nearly such difficult circumstances, and because of that, most breeders of horses do not face the same difficult choices. Still, the factors that allowed purebred dogs to reach this point are not entirely absent in horses. It is also true that because dogs are so pervasive in our culture, many people have had their views, particularly those about what constitutes a ‘proper breed’, influenced by the world of pedigree dogs. For that reason, I will present the situation with dog breeding as a cautionary tale for those interested in horses.

So what has happened to dogs? Three independent inquiries were made in the aftermath of the British documentary Pedigree Dogs Exposed. These produced three separate reports: the Bateson Report, the APGAW Report and the RSPCA Report. All three groups found that the health and welfare of purebred dogs were compromised, and highlighted two contributing factors. The first of these was selection for exaggerated anatomical features. The second was the dramatic increase of inherited disorders brought about by inbreeding.

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These observations were not new. In 1988 the British Council for Science and Society produced a report on companion animals. It noted the problems in the following statement:

An in­creasing number of hereditary problems are being recognised in companion animals, especially dogs. Many of these are the consequences of inbreeding or breeding for genetically defective animals. Some are the result of deliberate selection for abnormal or unnaturally accentuated physical characteristics for fad or fancy.

As that quote shows, both exaggeration and inbreeding were concerns twenty-four years ago. The observations made in the three reports were not new, but this time there has been public pressure to address the problems.

It is the efforts undertaken by the Kennel Club (KC) to address the first issue – the harmful anatomical distortions – that are currently the focus of much controversy in the British dog world. That controversy has created ripples over in the American dog fancy as well, with representatives from the American Kennel Club (AKC) insisting that such measures will never be taken in the United States. Meanwhile the second largest American registry, the United Kennel Club (UKC) has stepped forward to claim the high ground in addressing the issue.

This first issue will not be the focus of the posts made here. As important as the issue is to the dog world, it is not a widespread problem facing horse breeds. With a few exceptions – extreme heads in some halter Arabians, for example – breeders are not seeking to exaggerate the equine form. Horses are not anatomically malleable the way dogs have proven to be.

(These graphics come from a Belgian blog devoted to ethics in the breeding of German Shepherds.)

It is the second category of issues – those related to inbreeding – that are the bigger concern for horses. There is no question that within the horse world, there are endangered breeds with very small populations. Many of the draft and coaching breeds have experienced dramatic bottlenecks when the engine made them obsolete. It is also true that closed stud books and inbreeding are found in some horse breeds, and that some breeds have seen a rise in genetic diseases.

So why is inbreeding – in dogs or horses – a concern? Here is what the Bateson Report had to say:

Unquestionably inbreeding can lead to a loss of biological fitness. …. Inbreeding can result in reduced fertility both in litter size and sperm viability, devel­opmental disruption, lower birth rate, higher infant mortality, shorter life span, increased expression of inherited disorders and reduction of immune sys­tem function. The immune system is closely linked to the removal of cancer cells from a healthy body, so reduction of immune system function increases the risk of full-blown tumours.

These same observations are echoed in the other two reports. All three drew upon the expertise of geneticists for those conclusions. However much inbreeding is considered a valid tool by some animal breeders, the above statement is not particularly controversial within the field of genetics. Concerns about the downsides of inbreeding are pretty consistent across a large body of studies. It is the growing awareness outside that field that is new.

A few months ago, National Geographic did a feature story on the genetic variation found in dogs. One section jumped out at me when I was reading it, in part because the implications were terrible, and even worse I suspected many readers did not realize it. Perhaps pairing it with the above quote about inbreeding will make it more obvious. (Bold emphasis is my own.)

In short, while the Victorian breeders were crafting dogs to suit their tastes, they were also creating genetically isolated populations, little knowing how useful they might be to scientists in the future. The possibilities are especially abundant for cancer, certain types of which can show up as often as 60 percent of the time in some dog breeds but only once in every 10,000 humans.

Here is a similar observation from a peer-reviewed journal article:

Selection for phenotypic traits has resulted in the latent selection of genetic diseases and some breeds now have a high incidence of particular diseases, for example, the Samoyed, which has a risk ratio if 17.3 for diabetes and the boxer which has an unusually high incidence of various cancers.

The breed specificity of particular diseases lends dogs to be ideal candidates for comparative genetic association studies.

That is the precarious position of purebred dogs in 2012. Their genetically isolated populations have several hundred known genetic diseases. Because the dogs have been maintained in small subpopulations with decreasing genetic diversity, the incidence of those diseases has risen to the point that researchers have found them to be an invaluable resource. That may be good news for those seeking answers to human disease, but it is far from good news for the dogs themselves. It certainly should give pause to breeders of other animals that are considering taking (or continuing down) the same path.

It also merits thoughtful discussion by all involved with the animals affected – those that breed them, those that exhibit them and those that welcome them into their lives as companions.

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8 Responses to Why talk about dogs?

  1. Cindy Dalton April 4, 2012 at 11:12 am #

    I wonder if this also holds true in breeds that are more purpose-bred than looks-bred, say for example border collies?

    • The Equine Tapestry April 4, 2012 at 4:18 pm #

      I suspect people familiar with Thoroughbreds would tell you that it is not a guarantee. Despite being primarily bred for racing, they have a high level of inbreeding relative to other horse breeds.

      I do think that purpose-bred animals are safer than those bred purely for exhibition when it comes to avoiding exaggerated forms. Certainly in horses the closest breeders come to distorting anatomical features is in the halter entries of some breeds.

  2. oldmorgans April 4, 2012 at 3:02 pm #

    Very interesting. My horses are Morgans, a numerically small breed. And my especial interest are the Lippitt Morgans, who come from a tiny gene pool. What is the future for the pure Lippitt Morgan? I do not know.

    • The Equine Tapestry April 4, 2012 at 4:11 pm #

      Small groups within breeds like the Lippitts, and the Babsons (in Arabians), often come to mind when I read some of the papers on conservation in rare breeds. In some of those situations, you don’t necessarily have tight selection for the show ring, especially if show ring fads and fashions have passed them by, but the fact that they are often held by only a few individuals can leave them vulnerable for different reasons. One only has to look at the rare lines that show up from time to time in rescues to see how that might work. Each horse in a small pool that doesn’t get an opportunity to contribute is a loss.

  3. gj berg April 4, 2012 at 11:55 pm #

    PBS’ Nature two part episode “Dogs that changed the world” is being repeated tonight (and through out the next week) with second part next wednesday on my local PBS stations. Very interesting. The second part looks at a lot of the selective breeding that started in the Victorian era.

  4. eaequestrian April 5, 2012 at 7:35 am #

    I missed the Pedigree Dogs Exposed programme first time round but I watched the update recently with horror. Watching a CKC spaniel convulsing on the floor, screaming in agony from a neurological condition (PREVENTABLE by common sense breeding) that affects SEVENTY PERCENT of the population, in so much pain that he had to be put down afterwards made me feel physically sick.

    I know not all breeders are as horrible and apathetic as the ones in that programme were but urgh, I just wish there was something more that could be done. How you can in all honesty, breed an animal that cannot breathe without surgery, give birth without a C-section or needs to sit on ice packs at shows to stop it from giving itself heatstroke is beyond me.

  5. Kristina Pry April 7, 2012 at 4:38 pm #

    Actually, I believe in the Flat-Coated Retriever, incidence of cancer is almost 75%. I love the breed but I’m not sure I could own one for that very reason.

  6. Perly October 29, 2012 at 5:44 am #

    I own a Cavalier King Charles spaniel, and she does have a heart murmur, but thankfully has not shown signs of syringomyelia. She has also had 2 seizures that I have witnessed in 11 years. I was 10 when i bought her, but there is no way I would buy another dog without serious investigation into their histories.
    The degree of inbreeding in dogs (and other animals) has brought me to tears multiple times. It’s such an avoidable process, that we work so hard to avoid in other animals (Kakapo, and Takahe as NZ bird examples of small populations (under 200 birds each) that we are working so hard to avoid excessive inbreeding in) but we’re actively causing it in dogs. its so disappointing how people can not only turn a blind eye, but purposely cause it by selecting for line breeding/not allowing outbreeding. Man’s best friend indeed.