718 BREEDING DOWN THE LINE
BREEDING DOWN THE LINE
Inbreeding has attracted a great deal of attention recently, both in the human Asian community, concerned about cousin-to-cousin marriages, and in pedigree dog circles. In the latter however it’s not exactly a fresh topic. In his valuable book of 1905, The Kennel Handbook, the knowledgeable CJ Davies wrote: “We will turn to a matter which is indirectly touched upon in Mendel’s principles of heredity, that of the value of inbreeding. Perhaps no point in breeding is more subject to controversy than this one. From one breeder we may receive an alarming list of evils which will result from inbreeding; from the next we may receive nothing but praise of its virtues. Certainly the appearance and behaviour of some of our notoriously inbred animals is not a very favourable advertisement of its beneficiality; on the other hand we know that certain plants habitually fertilise themselves for apparently any number of generations, and not closer form of breeding can be imagined. Loss of size, sterility, loss of constitutional vigour, and, predisposition to disease are among the evils laid at its door. What we have to consider is, Are these caused by inbreeding? We should be inclined to answer: Indirectly, Yes; Directly, No.” He could have been writing yesterday; scientists and dog-breeders might answer quite differently.
In the last year or so in Britain a number of extremely important inquiries have been conducted into dog-breeding, and considering that very question one hundred years on. Each one has expressed concerns about breeding to close relatives in pedigree breeds. The Bateson report recommended the establishment of an Advisory Council (now set up under Professor Sheila Crispin) to address the issue. The cross-party Parliamentary Group’s findings also recommended greater scrutiny of dog breeding practices of such a nature. But for a century or so, close breeding to certain lines or sires has been accepted practice amongst pedigree dog breeders. In her informative book Advanced Labrador Breeding, published by Witherby in 1988, Mary Roslin Williams, herself a successful breeder of both show and FT champions, wrote: “to produce a strain of good ones, you must carry out a degree of line-breeding, possibly even using the dangerous practice of mild inbreeding in special cases. Top breeders hate the moment they have to use a complete outcross.”
She defined line-breeding as “a gathering of lines leading back in three or four generations to a known good dog or bitch or very often to one or two good dogs and bitches, with the rest of the pedigree filled with outcross names.” The famous Golden Retriever breeder Mrs WM Charlesworth warned against brother-sister matings but liked bitch to grandfather unions and favoured bitch to nephew matings. In the lurcher and terrier world, close matings can of course occur too. But when dogs are rated by their performance rather than their type or handsomeness, there are built-in safeguards. ‘Herrenvolk’ thinking has long been discredited in the human race!
Inbreeding is coming under greater scientific scrutiny as inheritable defects in pedigree dogs increase. One researcher in America found that in dog breeds there is a decline in the average life span of around 7% for every 10% increase in inbreeding. Dwarfism has been found in Pointer litters at inbreeding coefficients of 13 to 37%, whereas unaffected litters rated 0 to 24%. In a Foxhound pack, the conception rate with sperm of inbred dogs was 73% against 87% with outbred ones; average litter size was 7 against 9 and 4 against 6 at weaning. The sperm count was 70 against 367.
Swedish research shows that their pedigree dogs in 60 breeds had an average inbreeding coefficient of 14%. Most dog breeds with good-sized populations have a coefficient of inbreeding of 4-5%. Professional breeders of production animals such as cows, pigs, goats, sheep and horses consider that a coefficient of inbreeding of around 9% is risky. Why do breeders of production animals seek healthier animals than dog-breeders? Is it not mainly based on market value related to beef and milk production? Show dogs have no performance rating, just breeder-whim appearance.
Uninformed outcrossing is not the answer; there has to be research as well as vision. Leading geneticist Professor Steve Jones has stated that for pedigree breeds of dog 'a universe of suffering' is ahead with continued inbreeding. Fellow geneticist Bruce Cattanach has written: '...inbreeding has been ingrained in dog breeder psyche from the beginning and is hard to break, even when it is possible to show that it is not the most successful way to breed'. He went on to state that some pedigree breeds may well become extinct in our lifetimes without intervention, advising outcrossing to other related breeds. But who will listen to him; dogma will prevail and not just lurchermen will wonder at such folly - and such damage to long-established breeds. One of the weaknesses of the otherwise quite excellent Bateson Report into the state of pedigree dog-breeding in Britain was that it didn’t gather any valuable evidence on the genetic size of each registered breed. This report uses the expression ‘closely related breeding pair’ when discussing the mating of dams with sires, but doesn’t define what closely related actually means.
Inbreeding will not cause inherited problems if the problems are not present, in the genes, in the first place. The genetic size of a breed is crucially important; some ancient breeds are inbred and some relatively newly-created breeds are not. But breeding practices decide whether a breed founded a century ago is inbred or genetically diverse. Much can depend for example on the over-use of prize-winning sires. In 2010 a magnificent Hungarian Vizsla won best in show at Crufts; he had been a highly successful prize-winner since arriving here in 2005. During his first four years in this country, he produced 827 offspring, 517 being first generation from him. In that period just under 5,000 Vizslas were newly registered, which means that he sired more than 10% of the newly registered Hungarian Vizslas in Britain. The over-use of a top dog can end up contributing to a narrow genetic pool, which, without mandatory health clearances, can lead to an increased potential for inherited disease.
David Balding, Professor of Statistical Genetics at Imperial College, London, has advised: “Inbreeding is not the only cause of canine health problems, and perhaps not even the worst, but it is the easiest problem to fix…Find out the coefficient of inbreeding for a puppy before buying it…at least make sure that the puppy has four different grandparents, not one of them directly related to another.” The Finnish Kennel Club publishes the coefficient of inbreeding for dogs registered with them on its website, our KC must now do the same.
Inbreeding Depression is an acknowledged cause of small litter sizes, shorter lives and a reduced immune system in pedigree dogs, as Davies was noting a century ago. Dr Ian Ramsey of the University of Glasgow has stated: “Inbreeding leads to certain genes being concentrated in particular breeds, or even lines within breeds, and a lack of variation follows…However, dogs’ genes also determine how well their immune systems are at recognising their own bodies. If the ‘bad’ genes that stop a dog’s immune system recognising its own body are, accidentally, concentrated along with the ‘good’ genes for a certain coat colour, physical size, etc., then the dog will have an inherited tendency to suffer from autoimmune disease. This dog may well pass this tendency on to its puppies.” He went on to point out the only way of avoiding this is to avoid inbreeding as much as possible – accepting that as you do so a greater variation in other things will be introduced. Breeders can choose, their dogs cannot.