CANINE HIP DYSPLASIA
Canine hip dysplasia (CHD) is the most frequently encountered orthopedic disease in veterinary medicine practice. This extremely common heritable disorder of the growing dog can be influenced by nutrition. The period from 3 to 8 months of age appears to be important in the development of CHD, with the first 6 months generally thought to be the most critical. Early developmental findings of CHD, including joint laxity and coxofemoral anatomic changes, have been documented within 2 weeks of birth. Rapid weight gain in German shepherds during the first 60 days after birth has been associated with CHD at a later age. Frequency and severity of CHD are influenced by weight gain in growing dogs, especially if sired by parents with CHD or with a high incidence of CHD in their offspring. Dogs with weight gains exceeding breed standards have a higher frequency of CHD as well as more severe CHD than dogs with weight gain below the standard curve.(8)In one colony of fast growing Labrador retrievers, the triradiate growth plates of the acetabula fused at 5 months as determined by conventional radiography; normal closure of these growth plates in pups growing at conventional rates has been reported to occur at 6 months. Early fusion in the acetabulum is speculated to result in bone/cartilage disparities in the future and to predispose to dysplastic changes.(9) Limiting food intake in growing Labrador retriever puppies has been associated with less subluxation of the femoral head and fewer signs of hip dysplasia.
Overnutrition intended to maximize growth rate is incompatible with optimal skeletal development in many species. An early study suggesting a role of overnutrition in the development of skeletal disease in dogs was that of Hedhammer and colleagues in 1974(1); in an effort to study the influence of food consumption on the incidence of skeletal disease, these researchers performed an experiment comparing ad libitum versus restricted dietary intake in Great Dane puppies. The resultant skeletal pathology was markedly increased in the ad libitum group. This study heightened the awareness of the critical role nutrition plays in bone development.