Dog World Family Ties Grow too Tightby Larry Shook
(Reprinted by permission, we will be featuring this five part series of articles which originally appeared in The Spokesman-Review, Spokane, WA/Coeur díAlene, ID beginning February 19, 1995)
Itís the embarrassing intimacy that the Romanovs knew. The notorious bane of intermarried royals and remote ethnic groups from time immemorial -- thatís what ails purebred dogs today.
Call it inbreeding. Call it racial purity. Call it whatever you like. Family ties in the dog world have grown too close for the good of the species.
Since the first dog show was hosted in England in 1859, the worldís dog fanciers have mated closely related purebred dogs to produce winning show ring glamour. The practice has spelled disaster for canine health.
The "Canine Consumer Report," published by a California-based veterinarian group, lists 334 genetic and congenital diseases now common to purebred dogs thanks to misdirected breeding practices. Purebred dogs now suffer the highest incidence of genetic disease of any animals, humans included, according to Dr. Gustavo Aguirre of Cornell Universityís James A. Baker Institute for Animal Health. As a result, the nationís dog owners are paying through the nose -- more than $500 million annually, says Dr. William D. Schall of Michigan State Universityís College of Veterinary Medicine -- to cope with a situation that Mother Nature herself would never tolerate.
Geneticists stress that inbreeding alone doesnít cause this woeful condition. The real culprit, they say, is inbreeding without vigorous screening for genetic defects.
To understand whatís currently wrong with purebred dogs, it helps to review basic genetics. The dog has 78 chromosomes (compared with a catís 38 and the humanís 46). Within the chromosome is DNA, the stuff of which genes are made. DNAís business is to create protein molecules, known as "gene products," that govern the metabolism of life. Scientists guess that you and I and our dogs have about 100,000 genes and that we each run on about 30,000 gene products. Genetic disease can arise when the DNA goes wrong, causing a mix=up in the protein recipe. The upshot: more than 300 canine genetic diseases and counting.
Of types of genetic disorders, there are the basic three: 1) those resulting from a single mutant gene; 2) those caused by an unfortunate interplay of several different genes ("polygenic" defects, like hip dysplasia); and, 3) diseases spawned by flaws in the chromosomes themselves.
Genes exist in pairs, one from the mother, one from the father. When a genetic disease results from one mutant gene, the overbearing party is called "dominant." In the relatively few disorders passed on under a dominant scheme of inheritance, one parent is usually affected with the disease, and itís pretty easy to tell and comparatively easy to control the disease.
When it comes to recessive genes, however, it takes two to tango. A person or dog packing a recessive gene carries a secret in the dark privacy of the DNA.
Scientists say that genetic defects are a normal part of life. The average individual, human or canine, has a handful of them, but as far as Mother Nature is concerned, itís no big deal. This is because natural courtship practices guide individuals to marry or reproduce way outside their biological families. As long as they do, the chances of combining defective recessive genes are small.
When genetic disease does crop up, itís simply limited in the gene pool under the terms of survival of the fittest. Mother Nature doesnít "treat" genetic disease, she filters it via the unsentimental rigors of natural selection.
This brings us to the genetic bugbear now stalking dogs. In creating the dog, people replaced natural selection with artificial selection. Thereís no insurmountable problem here as long as health ranks prominently among the traits being artificially selected for. Among the nationís dog breeders there are only a hardy few at this moment making the efforts they could to breed healthy dogs.
The consequence of this laxness is exacerbated by the widespread practice of inbreeding. Inbreeding plus defective recessive genes equals -- well, ask royal families like the Hapsburgs and Romanovs about it.
After all is said and done, canine genetics come down to a fairly simple point that applies to dog breeders and dog buyers alike: You canít expect to dependably produce healthy dogs by defying natural law. Anyone who tries is betting against Mother Nature.
Next Issue: How dog buyers can improve their odds.
Larry Shook is author of "The Puppy Report," winner of the Ethical Issues Award of the Dog Writers Association of America.