IPFD Dog Health Workshop on Genetic Diversity – my “Best of Health” article for June 2022
On May 3, the International Partnership For Dogs (IPFD) hosted their second virtual workshop. Focusing on genetic diversity (primarily from a genetic tests/tools view), 60 participants – including representatives from IPFD and their partner kennel clubs, genetic test providers, breeders, and other key stakeholders – came together online to identify genetic diversity tools and resources, and to discuss priorities and actions for the benefit of all dogs. Half the attendees had been at the 2021 online workshop which discussed Genetic Test Reporting.
The distinguished panel included Prof. John Woolliams (The Roslin Institute, UK), Samantha Hauser (Embark, USA), Katy Evans (Guide Dogs, USA), Saija Tenhunen (Viking Genetics, FI), Pieter Oliehoek (Dogs Global, NL), and Sally Ricketts (University of Cambridge, UK), who shared their time and expertise with us. These speakers had provided short (YouTube) video presentations ahead of the workshop which were the pre-work for participants. The workshop was introduced by Katariina Mäki (Acting CEO, IPFD), a quantitative geneticist who previously worked at the Finnish KC.
International and collaborative genetic diversity management is important because different countries and KCs have different policies and tools available, so there is lots of learning that can be shared. Additionally, international populations of dogs/breeds could be sources of diverse genetic material and, increasingly, there are global breeding strategies being developed.
The problem of Popular Sires
John Woolliams said that everyone talks about Coefficients of Inbreeding (COI) but KCs and breed clubs should be having conversations about what’s happening in a breed and what else can be looked at, especially rates of inbreeding. KCs should be providing simple summary statistics on genetic diversity to breed clubs. Then, of course, the clubs need to understand how to use that information. The Popular Sire effect is potentially damaging for genetic diversity so, perversely, breed clubs publishing lists of the Top 10 winning show dogs might actually be encouraging less knowledgeable breeders to use these dogs at stud and add to the problem. Another attendee commented that one of the main concerns is that the whole pedigree dog culture is traditionally focused on the single successful specimen (or kennel). How can we shift the focus to the population of the breed as a whole? The issue with Popular Sires is that breeds are sidelining other potential sires who could be contributing to the gene pool.
Most UK breeders will be familiar with the Kennel Club’s online tool for Coefficients of Inbreeding. This is based on pedigree analysis and uses all the available pedigree information behind any particular dog. Joanna Ilska, the UK KC Geneticist, said we are discussing the number of generations to use in COI calculations but will still publish full pedigree values. If KCs worked together we could fill in missing import pedigree information. The UK has seen a reduced rate of inbreeding, reported in a paper published in 2015 (Lewis et al). This is mostly due to increased imports arising from the 2012 quarantine legislation change. Joanna said that an analysis of COI after removing imported dogs from the calculations also showed a reduction in inbreeding, and this occurred after introducing the Mate Select Tool. This may suggest breeder awareness has resulted in a change of behaviour.
What can breed clubs do?
John Woolliams said that the absolute COI value doesn’t matter and that COI will always increase in a closed gene pool (closed stud book). What matters is the rate of increase of COI. He also talked about some of the actions that breed clubs could (should?) take, for example, looking at pedigrees and average relationships (kinship) between dogs to understand how many different dogs contribute to each year’s puppies. In some countries there is a “neutering culture” where non-show puppies are sold with endorsements or contracts preventing them from being used for breeding. This too, leads to a loss of choice and genetic diversity. One of the participants commented “We, especially breeders, need to campaign that any healthy dog is a potential parent dog. By buying a purebred dog, you have become responsible for the heritage that breed constitutes.”
Jerold Bell emphasised that there are differences between pedigree COI and genomic COI. With the former, every puppy from a given mating would be calculated as having the same COI. The latter enables you to identify differences between individual puppies in a litter, because each puppy will inherit slightly different combinations of genes from their parents. Embark is one of the providers of genomic COI testing and it can sometimes be a shock for breeders to discover that their puppies’ genomic COI is significantly higher than a pedigree COI value. For example, Brenda Bonnett commented that for a sample of GSDs, genomic COI was around 40%, compared with 30% for pedigree COI. Other recent research papers have shown the same thing. Genomic testing is still relatively expensive for breeders to do, though.
Who owns the problem?
For individual breeders making decisions about their next litter, the most important generation is the potential sire and dam you have in front of you. You can’t do much about Great-great Grandparents! Calculating the COI of that potential litter when you know you’re not using the whole gene pool may be interesting but is not going to solve the problem of genetic diversity. The actual percentage of dogs bred from is small in most breeds. In Finland, they have found that only 2% of male dogs are used for breeding. Breeders should consider having more 1-time litters and avoid repeat matings. The idea of using double matings (2 stud dogs on 1 bitch) could be a way to generate a more diverse litter of puppies (who would need DNA parentage profiling).
Kennel Clubs can (and should) provide the tools and education to help manage genetic diversity within breeds, including offering the option to open stud books for appropriate cross-breeding projects. Breed clubs are best placed to look at what is happening across their breed (nationally and internationally) and should be using this information to provide advice and guidance to breeders.
Pieter Oliehoek made a really important point early in the workshop: the focus should not be on inbreeding but on genetic diversity. Breed clubs and breeders need to understand this important difference.
Brenda Bonnett reminded the attendees that any discussions and decisions on inbreeding or genetic diversity must be considered in the overall context of dog health. Extreme phenotypes bring with them health problems. There is no point “sorting out” genetic diversity if the dogs still can’t breathe, see, move or behave normally as dogs!