CANINE GENETICS

Hip Dysplasia is more prevalent in purebred dogs than in mutts.  Makes no sense?  Well it will when you read this thought-provoking article.

COMMON SENSE PREVENTION OF CANINE HIP DYSPLASIA

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Preventing CHD isn't just about genetics, x-rays, and breeding sound dogs to sound dogs. We already know that doesn't always work so what IS the key to good hips?

The cause of hip dysplasia is essentially, malformed joints but are hip joints genetic or environmentally affected? The various tests for HD were developed to help eliminate the "bad" genetics and create sound healthy dogs world but forty years later, hip dysplasia is still a major health problem.

Wayne Riser, DVM, founder of OFA (Orthopedic Foundation For Animals), circa 1975, tells a different story from what has evolved into popular myth about the "cause" of CHD (Canine Hip Dysplasia).

Dr. Riser studied hip dysplasia in dogs and explained it this way "In all mammalian embryos, the hip is laid down as a single unit from mesenchymal tissue, and it develops normally as long as the components are left in full congruity. The hip is normal at some time in the development of the mammal, and abnormal development occurs only when stresses pull the components apart.

"In the dog, the hip is normal at birth. Intrauterine stresses are not sufficient to produce incongruity of the hip. The first time such forces are great enough is when the pup begins to take its position to nurse.

"Observations of the disease in man, dog, and a number of other mammals for many years have culminated in the conviction that the bony changes of hip dysplasia, regardless of species, occur because the soft tissues do not have sufficient strength to maintain congruity between the articular surfaces of the femoral head and the acetabulum."

What Dr. Riser is saying is that muscles, ligaments, and tendons ("soft tissues") normally keep the head of the femur properly seated in the developing socket. But if there are abnormal forces on the joint, the soft tissues might be inadequate to stabilize the joint, and malformation of the hip socket will occur.

Most breeds developed to literally "cover a lot of ground" in the field, have fewer joint problems.  Breeders who work with breeds which, because of exaggerated size, bone, or overall loose construction, are more subject to hip dysplasia, have made many descriptive terms a part of doggy vocabulary. The key to preventing canine hip dysplasia (CHD) is found the words used to describe what many dog breeders consider VIRTUE in many breeds.

Instead of looking for "x-ray clear" or "OFA numbers" in a pedigree or genetic description, one should look at the structure of the dog. That means careful selection for muscle definition, tight skin rather than wet (loose skin), proper dense bone rather than "big bone", tight feet rather than "huge feet", and strong head instead of "bucket" or "massive head". In fact, the word "massive" should be stricken from the canine vocabulary. It describes an elephant, not a dog.

Those terms indicate excessive size, loose muscle tone, and/or skeletal mass too dense to be what nature intended for the canine. One has only to look at wild dogs, coyotes, foxes and wolves to see what works and therefore does not devolve into extinction. Having noted the way nature planned the carnivore, properly supported by balanced frame and muscle structure, we may have second thoughts about the structural problems we have created in the very creatures we so much adore…

Then there is this. The best genetic structure and muscle strength can be ruined. Dogs should not be whelped in slippery swimming pools. Puppies should not be over-fed, a problem that often begins before weaning age. Litters, even toy breeds, should be allowed out in the natural environment (footing) as soon as they step out of the nest to explore. CHD starts in the whelping box, not in the parents' hip scores.

So the takeaway on preventing structural problems including canine hip dysplasia (CHD) is this:

1. Do not breed for exaggerated bone size, especially in the "giant" or long-backed breeds.

2. Do not try to push puppies to early maturity or greater size.

3. Do not exaggerate Nature's basic design to sway ignorant buyers or dishonest judges.

SSI

SSI