Early Diagnosis of Canine Hip Dysplasia

Canine hip dysplasia (CHD) is a complex, multifactorial, progressive disease that develops during postnatal skeletal growth. CHD in the growing dog is clinically characterized by increased dorsal acetabular rim (DAR) slope and functional hip joint hyperlaxity that permit pathologic dynamic coxofemoral subluxation and the development of secondary joint remodeling and degeneration. Veterinarians are frequently challenged to diagnose CHD in growing dogs prior to the onset of these irreversible secondary changes so that proper treatment can arrest the progression of the disease and alter its pathogenesis.

Passive hip joint laxity refers to laxity that can be demonstrated in puppies by means of external veterinary manipulations (Ortolani test, Barden test, PennHIP distraction index). Some degree of passive hip joint laxity is detectable via PennHIP in all dogs. Passive hip joint hyperlaxity measured by PennHIP radiography is a heritable phenotype of CHD as well as a breed-specific risk factor for the development of osteoarthritis (OA). Detectable passive hip joint laxity does not always relate directly to the development of CHD symptoms or OA. From a therapeutic standpoint, the challenge faced by veterinarians is to detect or infer functional hip joint hyperlaxity in which dynamic subluxation occurs spontaneously during daily patient activities.

Signalment
Many large breeds of dogs develop CHD, but the most commonly presented breeds include Golden Retrievers, German Shepherds, Rottweilers, Labrador Retrievers, Chesapeake Bay Retrievers, Saint Bernards, and English Mastiffs. Puppies are seldom presented because of symptomatic concerns prior to 4 to 5 months of age. [...]