The Mayo Clinic is well known because it has been exceptionally good at solving the problems of the most difficult patients. It does this using an integrative approach to health care that might involve specialists in many fields that work together as a team to achieve diagnosis and treatment when specialists working independently have failed. Their extraordinary success using this integrated approach draws patients from around the world.
I think we need something comparable to the Mayo Clinic to help us address the growing burden of health issues in purebred dogs. Here's why.
Purebred dogs are plagued with a list of genetic disorders that numbers in the hundreds and grows longer every year. The costs to owners for veterinary treatment of breeds with high risk of disease are huge and growing, while at the same time millions of dollars are invested in research to understand, treat, or prevent these diseases. This burden of pain and suffering due to disease has caught the attention of animal welfare groups in several European countries, where legislation is being enforced that will restrict breeding of dogs that are likely to produce offspring with serious health issues. Norway has recently banned the breeding of English Bulldogs and Cavalier King Charles Spaniels in response to a lawsuit by an animal welfare group (scroll down the page at the link for English) on the grounds that the disorders common in the breeds cause a level of pain and suffering that violates Norway's Animal Welfare Act. For Bulldogs, the biggest problem is their brachycephalic skull (flattened face), which makes breathing difficult due Brachycephalic Obstructive Airway Sydrome (BOAS). It is likely that additional breeds will be added to those seen to be in violation of Norway's animal welfare laws. Furthermore, because there is similar legislation to protect the welfare of animals in countries around the world, the potential ramifications of enacting breeding bans on specific breeds are huge.
Faced with a health issue, the temptation of breeders is usually to assume that it is caused by a gene, with the result that they identify individual issues and search for solutions, one problem at a time. If a genetic disorder pops up in a breed, the scenario would be to search for the mutation, develop a mutation test that can be used on individual dogs, then avoid breeding dogs together that share the same mutations. This strategy can be effective if the disorder is caused by a single recessive mutation, but many problems are not; for these, affected animals and maybe also their relatives are removed from the breeding population on the assumption that there is some underlying genetic cause that should not be perpetuated. Breeders have been trying to manage many disorders this way, such as epilepsy, cancer, and renal dysplasia, but with little success. The consequence is that dogs (and their genes) are removed from the breeding stock, which reduces the size of the breeding population and increases the rate of inbreeding, both of which act to increase the expression of genetic disorders. Thus, breeds are stuck in a loop in which the actions of breeders to reduce the risk of genetic disorders actually increases the likelihood that some other issue will appear. It's an endless game of genetic whack-a-mole that is slowly driving breeds closer and closer to point where genetic deterioration will be severe enough that the breed goes extinct.
There are breeds that appear to already be at this extinction point. A very high percentage of Dobermans die of fatal DCM (degenerative cardiomyopathy), and recently the trend has been towards deaths in younger and younger dogs. Flatcoated Retrievers and Bernese Mountain Dogs rarely live past middle age, because they are stricken down by cancer. Most Cavalier King Charles Spaniels will suffer from mitral valve disease, and an early onset form of the disease takes dogs in their prime (Lewis et al 2011). Upwards of 70% of Cavaliers are also the victims of painful neurological conditions, Syringomyelia and Chiari Formation, which are also becoming increasingly common in other breeds with shortened muzzles and a tendency towards domed skulls (e.g., French Bulldogs, Brussels Griffons, Chihuahua). For these breeds and many others, the health issues common in the breed challenge the ethics of continuing to breed them.
What is missing in these statements is the recognition that the underlying problem is not with the genetics of individual dogs, but rather it is a problem of genetics across the breed. For many decades, most purebred dog breeds have been part of a registration system that is strictly closed to the introduction of dogs from unregistered parents. The result is a genetically closed population, a group of animals trapped on a genetically isolated island. All individuals are necessarily related, having descended from the same original genetic founders, so all breeding will be to a relative. Each breed is a genetically closed population from which genes can be lost through selective breeding or just by chance, but the genes lost cannot be replaced because of the closed registry. The result is that the gene pool shrinks relentlessly, and the population becomes more and more inbred. Eventually, genetically closed populations, like those of purebred dogs, suffer an increasing burden of health problems, low fertility, and shortened lifespan until, eventually, they simply go extinct. This is the road most breeds are on, and the kennel clubs have said nothing in their recent statements about the breeding ban in Norway that suggests a plan to change this trajectory. In fact, doing more of the same, even harder and more carefully, will actually make things worse.
Opening the stud books would slow the pace of new problems, but restoring health to the many breeds that are badly damaged will require a systematic and well-planned strategy. Unfortunately, however, there is nowhere for breeders to go for help.
Here is where I think we need something for dog breeds that is comparable to the Mayo Clinic. Note that I specified "dog breeds" and not individual dogs. The health problems of dogs are a consequence of the genetic health and structure of the population of animals in the breed, and the solution must first be directed at the breed population, not the individual dogs. The approach must be integrated and specific for the circumstances of each breed. Coming up with the right plan will require a broad range of expertise.
The genetic rescue of the Norwegian Lundehund has taken this approach. Inbreeding of the Lundehund is 80%, the highest ever recorded in a dog (perhaps also in any mammal?!!), and the breed suffers from extremely low fertility and a gastrointestinal disorder than can be fatal. Before designing a breeding plan for genetic rescue, a team of scientists performed genetic analyses on the pedigree database and another team analyzed genotypes of both the Lundehund and breeds identified as potential candidates for cross breeding. Using demographic information, genetic modeling showed how different breeding strategies would affect the efficiency of a breeding program, e.g., how many animals would be required and how long would it take for gains in genetic diversity. Each animal used and produced is evaluated for health and relevant traits, and additional breedings are planned based on the parameters of the genetic model being followed. Done properly, with good scientific oversight, a genetic rescue program like this can demonstrate the effectiveness of the breeding strategy in two generations. For the Lundehund, the second generation backcross has produced healthy animals of good type that also carry new genetic diversity that can be integrated into the breed population.
A place like this does not exist, yet it is desperately needed now, to help breeders tackle health problems before more breeding bans are imposed on potentially dozens of breeds. Cornell University, my alma mater (PhD.), recently received a $30 million gift to launch the Cornell Margaret and Richard Riney Canine Health Center at the university's excellent veterinary school. Another gift of $12 million will establish the Duffield Institute of Animal Behavior at Cornell. These funds fortify what already was a strong concentration of resources in canine health and genetics at Cornell. But neither will address what is arguably the most pressing issue affecting the health of dogs: the burden of genetic disorders that result from traditional but outdated breeding practices and ineffective strategies for preventing disease. While disease research has improved our understanding of the illnesses suffered by dogs, it rarely has substantial impact on health because it doesn't alter the landscape of underlying issues that result in the production of genetic disease in the first place. To make a difference, we need an approach that focuses not just on the dogs, but also on the breeders. Breeders need access to education, to up-to-date data about the genetic status of their breed, and (especially) to expert guidance to replace the blizzard of opinions available on Facebook as a source of factual, relevant information.
I don't see the problems facing dogs and their breeders being solved without a Mayo Clinic-like institution where a concentration of expertise can tease apart the layers of issues that must be addressed in order to restore dog breeds to health.
We know that genetic rescue is possible, but the infrastructure necessary to do it for more than a breed or two at a time simply doesn't exist. We know what we need to build if we can find the resources. The challenge now is to identify those that have a commitment to improving the health of dogs and can help pull together the resources to move this forward.
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