Hedhammar A, Olsson S E, Andersson S A, Persson L, Pettersson L, Olausson A, Sundgren P E
J Am Vet Med Assoc. 1979 May 1;174(9):1012-6.
Heritability of hip dysplasia was estimated to be about 0.4 to 0.5 when based on the radiographic evaluations of the hip joints of 2,404 German Shepherd Dogs born at The Armed Forces Dog Training Center in Sweden. The material included all dogs in 401 litters born at the Center from 1965 through 1973 that reached the age of 15 months. To be expected with such high heritability, frequency of hip dysplasia in the offspring was shown to be affected by the hip joint status of sire and dam as well as by the hip joint status of their parents and littermates. Even matings between sires with normal hip joints and dams with only slight dysplasia resulted in significantly higher frequency of hip dysplasia in the offspring, when compared with the frequency if both sires and dams had normal hip joints. Frequency of hip dysplasia in the progeny of sires with normal hip joints varied greatly. Since 1973, selection of the breeding stock has been based on hip joint status (phenotype) of the breeding animals and of their relatives as well as on what had become known about frequency of hip dysplasia in the litters already born (progeny testing). In this way, frequency of hip dysplasia in 347 dogs born at the Center during 1975 was lowered to 28%. This figure should be compared with the figure of 50%, which represents the frequency of hip dysplasia in the kennel up to 1970, when selection was not as strict as could be expected in a well-controlled kennel.
根据对瑞典武装部队犬类训练中心出生的2404只德国牧羊犬髋关节的X线评估，髋关节发育不良的遗传率估计约为0.4至0.5。该材料包括1965年至1973年在该中心出生的401窝中所有活到15个月大的犬只。鉴于如此高的遗传率，可以预期后代髋关节发育不良的频率会受到公犬和母犬髋关节状况以及它们的父母和同窝犬髋关节状况的影响。与公犬和母犬髋关节均正常时的频率相比，即使是髋关节正常的公犬与仅有轻微发育不良的母犬交配，其后代髋关节发育不良的频率也显著更高。髋关节正常的公犬后代中髋关节发育不良的频率差异很大。自1973年以来，种犬的选择基于种犬及其亲属的髋关节状况（表型）以及已出生窝仔（后裔测试）中髋关节发育不良的已知频率。通过这种方式，1975年在该中心出生的347只犬中髋关节发育不良的频率降至28%。这个数字应与50%进行比较，50%代表了该犬舍在1970年之前髋关节发育不良的频率，当时的选择不像在一个管理良好的犬舍中预期的那么严格。
