HIP DYSPLASIA
An article by Dr M B Willis
Hip dysplasia refers to a faulty fitting of the hip joint which is a ball (femoral head) and socket (acetabulum) arrangement. It is a polygenetically inherited trait amd can be assessed radiographically from a specific age. In the USA the minimum age for the OFA scheme is 24 months but in all other countries it is 12 months. Note that the objective is to reduce Clinical hip dysplasia (CHD) but the technique is to assess Radiographic Hip Dysplasis (RHD).
A high correlation will exist between those two features. Animals with severe RHD may show very few symptoms of CHD. This may arise because a dog may be very muscular or of a very tough character or both and thus it shows little sign of poor hips. However, breeding from severe RHD cases which do not exhibit CHD could lead to serious problems in their stock which inherited the poor hip status, without the character or muscularity and thus had severe CHD as well as RHD.
Hip Dysplasia will only be reduced if breeders deliberately select firstly from the best hip animals (without ignoring other features) and follow this up by using best progeny tested sires. Evidence on over 90,500 hips scores suggest that the best hip producing sires will have good hips themselves (if examined) but that good hipped animals will not necessarily all be good hip producers. However, the chances for sucess in hip status is greater with better parents and better hip pedigrees. As yet no sire sire has been located in any breed which had poor scored hips himself yet was a good hip score producer.
