Closing Canine Gene Pools

The short answer for the question regarding problems associated with selective breeding for specific qualities is yes. Is there scientific evidence to substantiate this claim? The answer again is yes. In my research, I have found evidence over and over again, if the gene pools of full-bred dogs do not expand, genetic disorders do increase. In 2003, at the AKC Canine Health Foundation Conference in St Louis, Mo, Dr. Jerold Bell DVM spoke about “Popular Sire Syndrome”. According to Dr Bell, there is a tendency to breed a winning sire with certified hip and eye clearance (meaning no hip or eye problems certified by a recognized association) or no epileptic breedings to epileptic dams. No matter how healthy the sire is, too much breeding can shift the gene pool in the direction of the sire and cause a loss of genetic diversity. It’s not a matter of what bad recessive genes the sire is carrying; it’s only a matter of when they will cause problems in future generations of the sire’s lineage. Dr Bell called this the “Founder’s Effect” Dr Bell further states that problems that inbreeding depression causes in purebred populations comes from the effects of deleterious recessive genes. When homozygous, they cause impaired health. Lethal recessive genes place a drain on the gene pool and can cause smaller litter size and new-born deaths. Other deleterious recessive genes can cause immune system problems and other diseases. (Jerold S. Bell, 2003)

     In an article for BARK magazine, Dr. Jane Brackman, PhD writes how 25% of the world’s dog breeds today were created in the between 1859 and 1900. Prior to that, she states “any hodge-podge of similar-looking dogs performing similar tasks was awarded the right to be called a breed”. She continues on to talk about the creation of dog shows such as Crufts and Westminster created strict breed standards, which led to a common gene pool. Dr. Brackman further states this continuation of the strict conformity to the standards led to homozygosity, which the downside is disease and unsoundness. She claims as a result of this “concentration of form”, today’s dogs suffer from more than 350 genetic illnesses. She interviewed Professor Mark Neff at UC Davis whose team has been researching this problem and has expanded on some results that was discovered during earlier studies. Dr. Neff and his team have found a single mutated gene that is sensitive to several modern medicines including anti-cancer meds, and an anti-heartworm drug called ivermectin. This sensitivity to the meds may cause death.  This mutation has gone unnoticed for over one hundred years. They discovered there must have been a common ancestor for at least the following nine breeds of dogs and the percentage of the frequency of the  mutated genes:  Collie (54.6%), Long-haired Whippet (41.6%), Miniature Australian Shepherd (25.9%), Silken Wind hound (17.9%), McNab (17.1%), Australian Shepherd (16.6%), Shetland sheepdog (8.4%), English Shepherd (7.1%) and the Old English Sheepdog (3.6%). (Jane Brackman, The Bark, Issue 34, Jan/Feb 2006) In a film released by the BBC called “Pedigree Dogs Exposed”, the very subject of selectively breeding and the consequences was the entirety of the film. If there was any doubt that closed gene pools, limited gene pools, in-breeding, etc. has any detrimental genetic effects on a dog breed, this film will cast out any doubts you may have. The dog breed that appears to be the major subject of the film is the Cavalier King Charles Spaniel. According to the film, in the UK this beautiful little breed is plagued with a neurological disorder known as “Syringomyelia” This is a condition where the back half of the dog’s skull is too small to accommodate the brain’s cerebellum. This causes an enormous amount of pain to the dogs. From watching the film, it appears to be nightmarish. This disease has been directly linked to the small gene pool for the breed. It is a problem for the breed in the United States as well. The film discusses other breeds with genetic disorders associated to the breeds. German Shepard’s hind legs appear to be lower to the ground and almost dragging. This is a direct result of the strict breed standard established by The Kennel Club UK. Another genetic mutation that was a total surprise to me is the Rhodesian ridgeback. According to Dr James Kirkwood, The ridge on the ridgeback is a sign of a genetic disorder known as dermoid sinus which is similar to human spina bifida. This is a condition whereby the backbone and spinal canal do not close prior to birth. The ironic thing is the puppies born without the ridge are considered mutations by breeders and are “put down”, but in reality actually born without the genetic defect. It was also brought out in the film although there are 10,000 pugs in the UK; in actually there is only enough genetic diversity for 50 healthy pugs. These are dogs that are plagued with numerous genetic disorders from selective breeding habits. (Pedigree Dogs Exposed, 2008) There are ways to perpetuate the breeds and create healthier lines. This is known and can be done. All that needs to be done is diversify the breeding stock by importing from other countries that have excellent breeding programs. The Swedish Kennel Club has banned all close in-breeding. The problem is as long as the show game is lucrative and profitable, the show breeders will continue business as usual until the genetic disorders will become so bad, the sires will become sterile or the dams will produce no litters. Looking at the big picture, would it be so bad if pure bred dogs could not breed anymore? All pure breeds are a result of man playing god and the consequences of this failed experiment are being felt by the innocent victims who rely solely on us to take care of them. Mixed breed dogs are stronger, healthier, live longer, and make great family friends. Maybe that’s the future of dogs.  Philip K Greis