Five misconceptions about canine hip dysplasia

From the John M. Olin Laboratory for the Study of Canine Bone and Joint Diseases

James A. Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University

-- Only hip joints and surrounding tissues are affected. Rather, evidence now indicates that the shoulder and knee joints and some intervertebral joints may show similar changes: the loss of cartilage, inflammation of the joint capsule, bone damage and the growth of spurs at the bone-cartilage interface. Hip dysplasia is simply the most conspicuous -- and most painful -- manifestation of this form of osteoarthritis.

-- Only dogs suffer hip dysplasia. While 50 percent of some of the larger dog breeds are afflicted, the disease is not unknown in humans. About 1 percent of the general human population suffers hip dysplasia, and the rate for the inherited disease is higher in some populations of American Indians. Many Navajos in New Mexico went through life with hip dysplasia until mothers stopped the traditional practice of strapping infants, straight-legged, to cradle boards and allowed babies to assume the more relaxed, bent-legged position. Replacement of diseased hip joints with artificial joints is one treatment, both for canine and human patients.

-- The absence of hip dysplasia in canine parents guarantees dysplasia-free pups. Unfortunately, out of 100 matings of "normal" dogs in breeds affected by hip dysplasia, 75 percent of puppies will be "normal" but 25 percent, on average, will have hip dysplasia. Genes for hip dysplasia are believed to be "masked" or hidden in some generations, making the elimination of the disease from breeding stock even more difficult. Canine hip dysplasia was first diagnosed in the 1930s, but probably has troubled domestic and wild canines for centuries.

-- All large-sized breeds of purebred dogs are candidates for hip dysplasia. Although the disease is particularly common among certain large breeds (from Bernese Mountain Dogs, Bloodhounds and Boxers to Rottweilers, St. Bernards and Welsh Corgis) mixed breeds of all sizes also are subject to hip dysplasia and not even the toy breeds are spared. However, the incidence is lower in small dogs. Large-sized breeds with a relatively low incidence of hip dysplasia include the Borzoi, Doberman Pinscher, Great Dane, Greyhound, Irish Wolfhound and Siberian Husky.

-- A hearty diet helps avert hip dysplasia. To the contrary, dogs that are genetically predisposed to hip dysplasia seem to benefit from a lean diet during their first two years. In one study beginning at eight weeks of age, pups that were restricted to a 24-percent smaller ration had a 46-percent lower occurrence of hip dysplasia than pups that could eat freely. Slowing the growth rate during the early months of life, some veterinary nutritionists now believe, can lessen the severity of hip dysplasia and even prevent it.