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HIP DYSPLASIA - IS SCREENING WORKING ?

First broadcast on www.provet.co.uk  


This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

A recent report raises doubts about the value of current screening schemes for hip dysplasia

One of the longest running canine health screening programmes in the UK  is the British Veterinary Association/Kennel Club Hip Dysplasia Scheme. About 100,000 radiographs have been examined since the scheme started over 30 years ago. The scheme involves the scoring of hip XRays for radiographic changes associated with hip dysplasia. In other countries eg Finland, such schemes have been running even longer.

The aim of these schemes is to identify individuals with radiographic evidence of the disease, and to encourage breeding only from animals with very low scores. The long term intention is to reduce the occurrence of the disease in predisposed breeds by reducing the genetic pool of affected animals, and earlier reports in the literature claimed success from  such schemes.

A Finnish report however by Leppanen et al (Journal of Small Animal Practice (2000) 41, 19-23) involved a review of 10,335 German Shepherd Dog records over a 12 year period (1985-1997) and it raises questions about the value of current screening programmes. They could find no evidence of genetic improvement in German Shepherds during the study period - even though in Finland the Kennel Club do not allow breeding from dogs unless they have only mild hip dysplasia (Grade C on their classification) or better.

The report reveals some other interesting findings. For example, there has been an increase in the numbers of offspring graded affected (C or worse) and a decrease the number graded excellent (grade A) when one of the parents were graded as normal (grade B) or only mildly affected (Grade C).

Most important of all, the report raises the whole question about whether or not such schemes can work. After all, it is well documented that hip dysplasia is the result of many factors - not just genetic inheritance. It is possible that stricter controls on breeding (ie only allowing breeding from dogs with Grade A (excellent) hips) might result in genetic improvement - but this needs to be proved. On the other hand, if breeding from stock selected on their hip XRay scores does not in fact improve the genetic pool in a breed - should we continue with the schemes, which cost considerable time and money to administer ?

Before we can say that current screening schemes are of little or no value more work needs to be done to verify the conclusions in this report. Nevertheless the relevant authorities should certainly consider the reports recommendations to change existing schemes to use best linear unbiased prediction (BLUP) breeding values rather than phenotypic selection very seriously.

Your views on the existing schemes would be welcome at feedback@provet.co.uk 

 

Updated October 2013