Estimates of environmental and genetic effects on hip dysplasia in Italian German shepherd dog population

This study aimed to investigate sources of variation and genetic parameters of hip scores (FCI method) for the evaluation of hip dysplasia (HD) in German Shepherd dog in Italy. Screening data for hip dysplasia of 18212 X-rayed dogs (provided by CeLeMaSche) were analyzed. Frequency of dogs not affected was 76.4% and the frequency of animals with mild, moderate and severe hip dysplasia was 18.0, 4.9 and 0.7% respectively. Data were analyzed with a Restricted Maximum Likelihood procedure using a mixed linear model to obtain variance component estimates for hip score. The pedigree file consisted of 26704 animals and contained ancestors for up to eight generations. Environmental effects influencing hip dysplasia were sex of the dog, age at screening, year and period of birth and experience of X-ray veterinarian. Recent years of birth showed a decreasing hip score, and this result was confirmed from genetic trend. Estimate of heritability was relatively low, ranging from 0.14 ± 0.01 to 0.17 ± 0.01. Maternal effect and random breeder effect had a small effect on the hip score. However, some breeders may have selected the most healthy animals for official screening, and this aspect should be taken into account because it might have caused bias in the results.