Progress in hip joint phenotype of dogs in the United States between the 1970's and early 1990's has been shown through results of a retrospective study using the OFA data base. This improvement was evident as an increase in the percentage of dogs classified as having excellent hip joint phenotype and a decrease in the percentage of dogs classified as having hip dysplasia (HD). The increase in percentage of dogs classified as having excellent hip joint phenotype was greater for German Shepherd dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers than for all dog breeds combined. In addition, the submission screening rate for these four breeds was higher than the screening rate for all dogs. Within these four breeds, the improvement was greatest for Rottweilers, which also had the highest screening rate.

Overall, low screening rates for breeds found in this study offer some insight into the problems involved with reducing the incidence of HD. The typical dog breeder is involved in breeding dogs for about five years. Thus, informed, experienced breeders are continually replaced with uninformed, inexperienced breeders who may not be as aware of the problems associated with HD or of the importance of participating in a screening program. In addition, many breeders choose which dogs they breed on the basis of the hip phenotype of individual dogs without knowledge of the phenotype of related dogs or previous offspring. It can be very difficult to get hip information on siblings and previous offspring due to the overall low number of dogs radiographed in a given litter (most dogs in a litter end up in pet homes). This is the slowest method of reducing the incidence of an undesirable trait or increasing the incidence of a desirable trait. The use of preliminary radiographs as early as 4 months of age can be used by breeders to add valuable information on the hip status of dogs they choose to use in a breeding program.

Hip dysplasia appears to be perpetuated by breeder imposed breeding practices, but when breeders and their breed clubs recognize HD as a problem and establish reduction of HD as a priority, improvement of the hip status can be accomplished without jeopardizing other desirable traits. Prospective buyers should check pedigrees and/or verify health issues with the breeder. If suitable documentation is not available, assume the worst until proven otherwise.

Do not ignore the dog with a fair hip evaluation. The dog is still within normal limits. For example; a dog with fair hips but with a strong hip background and over 75% of its brothers and sisters being normal is a good breeding prospect. A dog with excellent hips, but with a weak family background and less than 75% of its brothers and sisters being normal is a poor breeding prospect.

OFA's Recommended Breeding Principals

• Breed normals to normals
• Breed normals with normal ancestry
• Breed normals from litters (brothers/sisters) with a low incidence of HD
• Select a sire that produces a low incidence of HD
• Replace dogs with dogs that are better than the breed average