Dog breeding

the evolution of dog breeding


In the first edition of About the origin of species, Charles Darwin mentions dogs 54 times. He does this primarily because the extraordinary variation between dog breeds provides a wonderful illustration of the power of selection. For most of the approximately 15,000 years since their domestication, dogs have been selected by humans for their utility as hunters, scavengers, shepherds, guards or companions.

As modern breeds have become recognizable, the extent to which a dog aligns with the expected shape, size, and coat of its breed (called a “conformation”) has become more important. So significant, in fact, that just a few years before On the Origin of Species hit bookstores, the world’s first conformation-based dog show was held at Newcastle-upon-Tyne Town Hall. in England.

Read more: Is your dog happy? Ten Common Misconceptions About Dog Behavior

In 1873, the United Kingdom Kennel Club was trained to, among other things, regulate the exhibition and breeding of dogs. Similar organizations quickly followed in other countries. The judging and breeding criteria for conformation have been formalized in breed standards which are now administered by dog ​​clubs around the world.

Unfortunately, breeding for the standard in some breeds has resulted in serious compromises in health and welfare, especially in cases where the wording of the standard has encouraged the exaggeration of certain characteristics.

An Afghan hound at the annual Crufts Dog Show at the NEC Arena in Birmingham, Britain, 7 March 2019.
EPA / Nigel Roddis

Breeds to watch out for

The kennel club Breed watch highlighted around 15% of breeds as having ‘breed-specific conformation issues that can lead to health issues’ and an additional 4% of breeds in which’ some dogs have visible conditions or exaggerations that can cause pain or discomfort ”.

Fortunately, there is now global coordination to address these issues. The International Partnership for Dogs (IPFD) who works with many of the world’s leading breed regulatory organizations, points out “conformation extremes”.

Without up-to-date prevalence data on each disorder, we cannot be sure of the effectiveness of watchlists or changes in breed norms in combating these disorders. Additionally, in 2009-2010, one of us (Paul McGreevy) helped show that while some of the worrying conformation issues relate to breed standards, others are hereditary disorders unrelated to breed standards.

So even if there were no breed standards and dogs were raised purely for their health and well-being, many inherited disorders would still occur. In fact, the vast majority of inherited disorders have nothing to do with conformation.

All inherited disorders (and all desirable inherited traits) are, in essence, the result of random DNA mutations that have occurred and continue to occur in all species.

A boy leads a Saint Bernard at a dog show in Bishkek, Kyrgyzstan, May 05, 2019. The International Kennel Club Dog Show was held in Bishkek.

The number of known inherited disorders varies widely among species, primarily reflecting the scale of research efforts. For example, the number of monogenic disorders documented in humans is more than 5,300, while the figure for dogs is less than 300. Since many inherited disorders that occur in humans could also occur in dogs, the current number for dogs is probably just the tip of the iceberg.

A worldwide research effort is providing an ever-increasing number of DNA tests for known canine inherited disorders, helping (in many cases) to rule out the disorder. National dog clubs offer useful tips on testing and public access to test results on individual dogs. The IPFD provides global information to breeders on the harmonization of genetic tests for hereditary diseases in dogs.

One of us, Paul McGreevy, was part of an international team that developed a risk assessment criteria to determine priorities for the research and control of inherited disorders. A major component of this score is the prevalence of a disorder in a particular breed.

American Akita dogs wait their turn to be judged at a dog show in Bishkek, Kyrgyzstan on May 05, 2019. The Kennel Club International Dog Show was held in Bishkek.

Estimate the prevalence of disorders

Fortunately, digital health has entered the veterinary realm and is expected to provide, for the first time, comprehensive estimates of the prevalence of the disorder.

Paul is the president of VetCompass Australia, based on the great success United Kingdom VetCompass which he helped establish ten years ago. It is the first Australia-wide surveillance system that collects clinical records of diseases and treatments in companion animals.

Bringing together Australia’s seven veterinary schools, VetCompass Australia collects clinical records from hundreds of veterinarians across the country for researchers to interview. Analysis of these records will reveal trends in the prevalence of inherited and acquired diseases, identify effective treatments, and help veterinarians and breeders improve the quality of life of dogs.

Read more: Vets can do more to reduce the suffering of flat-faced dog breeds

The vision of this surveillance system is that it will someday provide real-time data on the prevalence of each known disorder and show the effectiveness of different control strategies. Real-time data will also sound the alarm bells on clusters of new troubles as they emerge.

Completing VetCompass is My Breed Data, a Finland-based website that collects the results of genetic analyzes from a large number of dogs to identify mutations known to cause particular hereditary disorders. Among other things, this information provides warning signs as to which breeds contain which harmful mutations.

What about hybrid vigor?

Hybrid vigor for a particular trait is the extent to which, on average, puppies resulting from mating of a purebred female of one breed with a purebred male of another breed are better for that trait. than the average of the two parent breeds for this trait. trait.

Evidence from other species suggests that hybrid vigor in dogs may occur to a limited extent in traits related to health, well-being and fitness for use. The greater the genetic difference between two breeds, the greater the vigor of the hybrid should be in the offspring of the first generation between these breeds.

Specifically, the offspring of the first generation are unlikely to develop recessive disorders present in only one of the two parental breeds. On the other hand, they can obviously develop inherited disorders which are present in both parental breeds, which is often the case with disorders like hip dysplasia.

Husky dog ​​waiting his turn to be judged at a dog show in Bishkek, Kyrgyzstan, May 05, 2019. The International Kennel Club dog show was held in Bishkek.

It is important to note that selection beyond first generation crosses reduces the vigor of hybrids and triggers unpredictable variations. This is good news for traditional breeders, as it means that the most desirable hybrids are the offspring of two pure breeds, rather than those bred afterwards.

Mixed-breed (or “designer”) dogs are nothing new: the Kennel Club has been established. record them for over 50 years. Unfortunately, most peer-reviewed studies of canine crosses do not allow us to estimate actual hybrid vigor, simply because they do not report parentage of mixed breed dogs.

Fortunately, getting some evidence of actual hybrid vigor in dogs should be relatively simple: it simply requires that veterinary records include parentage of mixed-breed dogs, when known.

Read more: Are you walking your dog enough?

The information collected by VetCompass and MyBreedData will provide a solid basis for prioritizing research and control programs for inherited disorders in breeds. It also has the potential to shed valuable light on the extent to which hybrid vigor exists in dogs. Armed with this information, breeders will be able to combine new technology with the skills of traditional dog breeding to breed dogs that are more likely to look great, healthy, and thrive in the kennels we have. offer them.