Someone on the Working HPR forum discussion on Slovakian Rough Haired Pointer health thread posted a link to an interesting article by Angela Helen Harvey. The article is available to read as a PDF here. The discussion today moved on to how possibly insignificant and minor conditions may add up to form a pattern and if a breed is too inbred that risks to these conditions increase.
Here are some excerpts:
"In an inbred individual, the chance that both parents have passed on identical genes...increases. This situation diminishes the body‟s capability to mount an effective immune response. Such dogs are more prone to infections and are more likely to suffer autoimmune disease or allergies...
Overall the canine population probably contains as much MHC diversity as it ever did, BUT when we begin dividing the species into individual breeds, and then we line and inbreed within these breeds the available MHC allele become limited.
Without diversity within the MHC, the dog is much more vulnerable to disease. If the disease is bad enough, the dog may die...
The regular use of popular sires over several generations can play havoc with MHC diversity...if a significant portion of a breed descends from a relative few individual dogs the population may not be able to respond effectively to the next canine plague that comes along.
Inbreeding has been the norm in domestic dogs for more than a century. As we have said the technique is used quite effectively to “fix” traits deemed desirable. The practice of inbreeding to improve breed traits has inadvertently led to a reduction of MHC diversity within the individual breeds. Unfortunately most Breeders do not appreciate that continued line Breeding is a form of Inbreeding!
Popular sire use is especially pernicious because each such sire can have only two MHC haplotypes--nowhere near the hundreds that exist in the canine genome. Therefore, when a significant portion of a breed descends from one individual, those dogs‟ resistance to infectious disease or susceptibility to autoimmune disease can be seriously affected. No dog affected with chronic autoimmune disease or serious allergies should be bred. Auto Immune diseases include “Collie nose” which is an autoimmune dermatitis of the face. Another growing problem created by a faulty immune system is generalised Demodectic Mange."
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