Hip Dysplasia (HD) in Collies
Most dysplastic dogs are born with normal hips but, due to genetic and environmental factors, the soft tissues surrounding the hip joints may develop abnormally as the puppy grows with an accompanying laxity or looseness in the muscles, cartilage, connective tissue and ligaments. As the joint is not supported, the femoral head and the socket move apart producing an unstable joint. It is this instability that causes all subsequent problems.
If the cartilage that lines and cushions the hip joint is damaged by trauma or excessive exercise it loses its thickness and elasticity. This in turn reduces its shock-absorbing qualities during movement. In an attempt to stabilise the joint and decrease pain the animal lays down new cartilage, but this is a slow process and in the meantime the femoral head is worn and flattened. New bone (bone spurs) is produced at the edges of the joint surface, ligaments and muscle attachments which decrease the dog’s range of motion. It is a constant cycle of cartilage damage, inflammation and pain - the more the joint is damaged the less able it is to resist further damage.
Environmental factors such as calorie intake, exercise levels and weather can all affect the severity of clinical signs. There are a number of dysplastic dogs with severe arthritis, that can run, jump and play as if nothing were wrong, and some dogs with minimal radiographic changes that show severe lameness.
Hip Dysplasia should be taken seriously because, unlike eye problems, it is a painful condition which affects the life quality of the dog as the arthritic changes taking place within the joints cause great discomfort.
The KC/BVA runs a hip scheme, and names of dogs passing through the x-ray testing procedure are published in the quarterly Kennel Club Breed Records Supplement. Hip Dysplasia can only be diagnosed on adult dogs over the age of twelve months.
In the UK the Kennel Club appoints a specialist veterinarian who scores the hips on a points system, up to a maximum of 53 each hip (total 106). The total score of both hips gives the hip score for a particular dog. The nearer the total score is to zero, the better the hips.
As at 1 November 2007 only 860 Rough Collies had ever been x-rayed for HD in the UK, with a further 42 tested during the following twelve month period. This total of 902 compares with 64,000 Labradors and 31,000 Golden Retrievers during the same period!
The mean (average) score for Rough Collies is currently 12 so, in order to improve the breed’s overall hip status, it is advisable to breed from stock with better than average score (between 0 and 12).
The Kennel Club unfortunately does not legislate for imported dogs to be free of HD, although most other countries require a ‘Pass’ for dogs they import. But now the problem begins – many countries have completely different methods of assessing the x-ray plates so how do we compare the results? Jay Kershaw of the Aritaur Dobermanns kindly supplied me with the following table which you will hopefully find useful.
The table below shows the comparisons between the hip scoring schemes of various countries: