PREVALENCE AND INHERITANCE OF AND SELECTION FOR HIP-DYSPLASIA IN 7 BREEDS OF DOGS IN SWEDEN AND BENEFIT - COST-ANALYSIS OF A SCREENING AND CONTROL PROGRAM

Objective-To determine the prevalence and changes over time in the pre valence of hip dysplasia; to ascertain whether prevalence or severity of hip dysplasia was associated with sex of the dogs, age at which cox ofemoral joint status was evaluated, or ancestral background; to deter mine the effects of selective breeding; and to conduct an economic eva luation of the hip dysplasia program operated by the Swedish Kennel Cl ub. Design-Analysis of radiographic evaluations of coxofemoral joint c onformity. Animals-83,229 dogs from 7 breeds registered by the Swedish Kennel Club. Procedure-All radiographs were scrutinized by a single r adiologist (LA), and coxofemoral joint conformation was classified as normal or dysplastic, with the degree of dysplasia classified as 1, 2, 3, or 4. Results-Decreasing prevalence of hip dysplasia corresponding to selection of breeding stock and high heritabilities was found. Sex differences were documented in 3 of the breeds. This was interpreted as breed differences in the distribution of genes related to hip dyspl asia. Economic analyses showed that costs of screening and registratio n of coxofemoral joints was less than the value of dogs estimated to h ave been saved from moderate, severe, or very severe hip dysplasia in 6 of the breeds. Clinical Implications-Documented effects of age sugge st that ail dogs should be screened at the same age, rather than scree ning a few dogs at an older, more revealing age. In screening and cont rol programs based on an open registry with access to family records, decreasing prevalence of hip dysplasia can be expected, and related to selection of breeding stock.