EVALUATION OF THE EFFECT OF USING THE STANDARD OFA SCORING METHOD AS A SELECTION CRITERIA FOR BREEDING TO IMPROVE THE HIP CONFORMATION IN CANINES

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EVALUATION OF THE EFFECT OF USING THE STANDARD OFA SCORING METHOD AS A SELECTION CRITERIA FOR BREEDING TO IMPROVE THE HIP CONFORMATION IN CANINES

Ann L. Reed, D.V.M., M.S., G. Greg Keller, D.V.M., M.S., Dale W. Vogt, Ph.D, Mark R. Ellersieck, Ph.D.

Introduction/Purpose

Radiography is the most commonly accepted diagnostic method at this time for large-scale screening of dogs for Canine Hip Dysplasia (CHD). Unfortunately, there is no radiographic technique that precisely reflects the genetic composition of a dog or the risk for passing CHD to the offspring. The purpose of this study was to evaluate the effect of using the standard OFA scoring method as a selection criteria for breeding to improve progeny hip conformation.

Methods

Data sets of pedigree records for the English Setter (ES), Portuguese Water Dog (PWD), Chinese Shar Pei (CSP) and Bernese Mountain Dog (BMD) were merged with OFA hip scores to create the database used in this study. Analyses of various fixed effects (sex, age when radiographed and year of birth) and random effects (sire, dam, and sire by dam interaction) on the variation observed in progeny hip conformation scores were performed. In addition, heritability and analyses of the annual percentage of breeding animals screened and concurrent change in progeny hip conformation were evaluated.

Results

Progeny sex differences in all breeds were not significant (P>.05). Effects of age at radiographic scoring were significant (P<.05) in all breeds except the CSP. The effects of year in differences among percent dysplastics and normals in all breeds was significant (P<.05). Mid-parent-offspring analyses yielded heritability estimates of .17+.05, .30+.06, .31+.05 and .30+ for the ES, PWD, CSP and BMD, respectively, with a pooled value of .26+.03. Individual dam and sire effects were significant (P<.05) and the interaction of the two on progeny hip scores was not significant (P>.05). There was a highly significant decrease (P<.01) in the percentage of dysplastic progeny with excellent and good paired matings compared to fair paired matings. There was an annual percent increase in the percentage of normal progeny and concurrent decrease in the percentage of dysplastic progeny. This paralleled the annual percent increase in normal scored breeding animals bred.

Discussion/Conclusions

Results of this study are consistent with the additive, polygenic hereditary nature of CHD with equal genetic contributions from the sire and the dam. The pooled breed heritibility of CHD was found to be in the moderate range. Percentages of normal progeny significantly increased as pairings involving excellent and good sires and dams replaced parents with increasingly poorer classifications. This study confirms the world’s hip registry recommendations to breed radiographically normal to normal. If fairs are used in a breeding program, lower progeny dysplastic rates may be obtained by breeding to excellent or good mates.