The sins of the father are laid upon his children – “Best of Health” March 2016
I want to start with an addendum to my last article; with thanks to Lesley Bloomfield who is Joint Breed Health Coordinator for English Springer Spaniels. Lesley kindly pointed out that the ESS breed were involved with a “One Medicine” project as far back as the 1980s. She writes “Regarding the ‘one medicine’ ‘one health’ issue, it was really ‘back in the day’ (1980s) that Dr Bryan Winchester from King’s College, London was working on Fucosidosis in young children. A study using an ‘enzyme test’ was set up for English Springer Spaniels that was used until a young Barbara Skelley completed her PhD using samples of RNA taken from ESS owned by breeders keen to help. So impressed were her examiners with the work submitted that research followed that not long after led to a DNA test.”
Another article that has generated a lot of discussion among Breed Health Coordinators is Dr. Carol Beuchat’s “Three key strategies to reduce genetic disorders in dogs” published on her Institute of Canine Biology blog. Carol starts by saying “In many breeds, dodging genetic disorders is becoming a significant problem because troublesome recessive mutations can be widespread in the population.”. She goes on to discuss something I have pointed out before in my articles; that is the futility of many breeders’ determination to adopt a “search and destroy” strategy to eliminate genetic mutations by finding ever more DNA tests. There are many more genetic mutations than there are DNA tests and even if we had tests for all of them, it would be impossible for breeders to make breeding decisions to prevent every risk.
Her stark conclusion is that “We can spend millions on research and testing to battle genetic diseases in dogs, but we cannot win this fight unless we change the breeding strategies that produce the problems in the first place.”
The three strategies in Carol’s article are:
- Increase the number of breeding animals
- Eliminate Popular Sires
- Use strategic outcrossing to reduce inbreeding
I’ve written about the first two of these in the past. If a wider range of stud dogs is used, or more puppies are used in breeding programmes, then this will have a positive impact on breed populations (I talked about encouraging owners of “pet” puppies to breed with them). We would then have more individual dogs and bitches producing the next generation. The second point is actually a specific dimension of the first one. Popular Sires disproportionately contribute their genes to the next generation, with all the consequent risks of doubling-up on deleterious recessive mutations in later generations. Every breeder who jumps on the bandwagon by using a Popular Sire can be held responsible for genetic problems that pop up as a “surprise” subsequently. In reality, these problems should not be a surprise because that’s exactly what you’d expect when recessive mutations combine down the line.
“The sins of the father are to be laid upon the children” is a quote from Shakespeare’s Merchant of Venice. The dog breeder’s equivalent should be “The sins of the Popular Sire are laid upon his puppies and his puppies’ puppies”.
The FCI’s International Breeding Strategies paper recommends “As a general recommendation, no dog should have more offspring than equivalent to 5% of the number of puppies registered in the breed population during a five-year period. The size of the breed population should be looked upon not only on national but also on international level, especially in breeds with few individuals.”
In an earlier article where I discussed the Kennel Club’s 2015 paper on genetic diversity, Carol’s third point was also raised. Her suggestion about “strategic outcrossing” could be as simple as planning matings with dogs from distinct sub-populations such as imports (but beware the Popular Import Sire), different coat/variety, or different disciplines (e.g. working/show).
In some of the different varieties of Dachshund, we have seen a number of imported dogs who have clearly contributed new genes to the population. While some people will argue that not all the imported features/traits have been beneficial, overall we have seen a positive impact in reducing levels of inbreeding. Like the Belgian Shepherds, Dachshunds also have the interesting possibility of cross-variety matings and the KC has previously given permission for this to be done. Some breeders have taken the opportunity to import cross-variety bred puppies which give a potential double benefit in terms of genetic diversity.
I’d perhaps add a fourth suggestion to Carol’s three and it’s a very simple one that every breeder could adopt immediately: Use the KC’s MateSelect to choose breeding combinations that result in litters with a COI below the breed’s current median COI. This will (slowly) help to reduce a breed’s overall level of inbreeding. There is, of course, my previously noted caveat that the COI data on MateSelect may only be for 3 generations for imported dogs which may result in an under-estimate of the COI of any planned matings.
The discussion about Carol’s article among Breed Health Coordinators largely centred on the uphill struggle they have to persuade their breed communities to read any of these articles, let alone begin to change their behaviour when breeding. One BHC said she was exhausted trying to explain and “apparently, you have to have been breeding for the usual 40 years to have any idea”. Another said “I sense that many breeders don’t believe what they do read or are being told by scientists/geneticists and if they do, they find it difficult to apply the information to what they are doing. Sometimes this might be because there is still a deep-seated feeling of mistrust – especially when it comes to anything sent out from the KC – or because they just don’t understand it.”
I’ve argued before that breed health improvement is a change management issue, not a scientific one. It requires individual breeders and buyers to change their behaviour. We have to keep nudging people in the right direction by sharing data, evidence and practical examples of what actions can be taken. Remember, “without data, you’re just another person with an opinion” [Dr. W Edwards Deming – statistician].