Friday, December 26, 2008

Flawed Paws

Dr. Paul Mcgreevey writes in New Scientist:

In the wake of the documentary [Pedigree Dogs Exposed], leading animal welfare charities such as the Dogs Trust and the RSPCA have spoken out against pedigree dog breeding, and withdrawn their support for Crufts, the UK Kennel Club's flagship event. It is time for a new approach to dog breeding: that is based on a comprehensive understanding of their biology; that values health, longevity and suitable temperament; and that ensures we get the best out of companion dogs by helping them to help us.

Many veterinary geneticists saw the crisis that now faces the Kennel Club looming many years ago. The closed studbook system used by pedigree breeders inevitably involves inbreeding that increases the risk of inherited disorders caused by recessive genes. Such disorders are now recognised in all established breeds of dogs and cats, as well as horses, farm animals and a growing number of captive exotic species. But the problem is worst in dogs, which have been intensively bred within the closed studbook system since Victorian times. Many dogs now have inherited disorders that cause them to suffer so much that it is unkind to keep them alive.

Worse, pedigree dog breeders compete to produce animals that conform to written standards, which may include morphological and behavioural traits that compromise quality of life. These traits were incorporated into the first breed standards when dogs left the working arena and entered the world of dog shows in the late 1800s, and many of them may have been valued by early dog domesticators because they served a particular purpose. Unfortunately breed standards now tend to prioritise appearance over functionality.

For example, the breed standard for Weimaraners demands that the chest is "well developed, deep" while the abdomen is "firmly held" and the flank is "moderately tucked-up". These requirements may help to make Weimaraners appear athletic but veterinarians know that breeds with deep chests are at risk of gastric dilation and torsion, an extraordinarily painful, life-threatening condition in which the stomach bloats with gas and can become twisted. Or take the Pug, which according to its breed standard should have eyes that are "very large, globular in shape". Breeders oblige the judges and select for this feature, leaving Pugs with eyes that bulge so badly their lids scarcely meet well enough to wipe the eyeball clean. The poor dogs undergo a lifetime of chronic conjunctivitis that eventually scars over the cornea and blinds them.

The emphasis in dog breeding needs to shift. To minimise rates of inherited disease, closed studbooks may need to be abandoned.There are also calls for each breeding population of dogs to be placed under surveillance, so that new disorders can be tracked as they emerge.


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