Heritability and epidemiology of canine hip-dysplasia score in flat-coatedretrievers and Newfoundlands in the United Kingdom

Hip dysplasia (malformation of the coxofemoral joint) in dogs is a major he alth problem for which the British Veterinary Association (BVA) had set up a control scheme in 1965. Based on scoring nine components of the radiograp hs of both the left and right joints, the degree of hip joint malformation is now quantified by an overall hip score (a measure of the condition of th e hip joint). The hip scores of 1258 flat-coated retrievers and 1566 Newfou ndlands (registered with The Kennel Club in the United Kingdom) were analys ed after merging with Kennel Club pedigree data for 19 036 flat-coated retr ievers registered by 1995 and 14 336 Newfoundlands registered by 1997. The merged data included the animal's identity, date of birth, sex and hip scor es and also similar records for the dog's relatives including the hip score if the relative had been tested. In recent years, breeding has been increa singly from tested parents. There has been some reduction in offspring hip scores - presumably because breeders avoided breeding from males with very high scores. However, a much greater reduction in offspring hip score would be achieved by stricter science-based selection of potential sires and dam s. Regression modelling quantified the positive relationship between offspr ing and parental hip scores. The genetic heritability of hip scores was lar ge and significant in both breeds (particularly from dams). The breeders in UK tended to use healthy sires for breeding but they have taken less care in selecting dams. Our regression models emphasise the need for both sires and dams, particularly dams, to be healthy with very small hip scores. (C) 2000 Elsevier Science B.V. All rights reserved.