What are Hip and Elbow Dysplasia?
Both hip and elbow dysplasia are developmental disorders leading to malformations of their respective joints. Hip dysplasia (HD) is a developmental orthopaedic disorder, characterised by the development of coxofemoral (hip) joint laxity. The aetiology of HD is undetermined, but the effect of hip laxity is to reduce the stability of the joint, resulting in partial or complete dislocation (subluxation and luxation) during weight bearing. Over time, this leads to the abnormal wearing of the articular surfaces and the development of degenerative joint disease (DJD), such as exostosis (abnormal bone growth) and cartilage erosions. Clinical signs of hip dysplasia may first appear in puppies as early as five months of age, and it affects the mobility and well-being of the dog for the rest of its life. The primary lesions can be treated surgically, but the secondary osteoarthritis that develops from the abnormal wearing of the joint is irreversible, with salvage surgery such as hip replacement as the only option. Elbow dysplasia (ED) is a related disease, covering a number of distinct malformations and malfunctions of the elbow joint, and like HD, can also lead to osteoarthritis of the affected joint.
Hip and elbow dysplasia are multi-factorial diseases involving multiple genes interacting with the environment. Environmental factors can include such things as weight, injury at a young age, over exertion on hip or elbow joint at a young age, and diet. Hip and elbow scoring schemes provide phenotypic measures of joint laxity (dysplasia) and associated bone re-modelling. Four major hip scoring schemes exist:
British Veterinary Association/Kennel Club (BVA/KC) scheme – in UK, Ireland, Australia, New Zealandhttp://www.bva.co.uk/canine_health_schemes/Hip_Scheme.aspx
Orthopedic Foundation for Animals (OFA) – in USA, Canada http://www.offa.org/
Fédération Cynologique Internationale (FCI) – in Europe, Russia, South America, parts of Asia http://www.fci.be/commissions.aspx
Hip score has a relatively high heritability in UK Labrador Retrievers of 0.35 (Lewis et al. 2010a) indicating a strong genetic influence on predisposition to the disease and it can be demonstrated that improved genetic evaluation procedures will lead to higher selection accuracies and a quicker reduction in disease prevalence (Lewis et al. 2010a, 2010b). Hip and elbow dysplasia have a genetic correlation of 0.4 thus selection against hip dysplasia should also result in selection against elbow dysplasia (Lewis et al. 2011).
Further Information Links:
Lewis, T.W., Blott, S.C., Woolliams, J.A. (2010a) Genetic evaluation of hip score in UK Labrador Retrievers. PLoS One 5(10) e12797.
Lewis, T.W., Woolliams, J.A., Blott, S.C. (2010b) Genetic evaluation of the nine component features of hip score in UK Labrador Retrievers. PLoS One 5(10) e13610http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal