Feline Hip Dysplasia

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Normal hips
Radiograph of a cat with normal hips

Radiograph of a cat with HD, degree 3, in both hips

When you hear people talk about Hip Dysplasia and that radiographs have been taken most people are referring to dogs. But this problem also applies to cats in general. Hip Dysplasia is a hereditary defect in the socket joint (in the pelvis) which means that it is not as deep as it normally should be. Because of this the ball does not fit exactly in the socket joint and the surfaces begin to rub against each other, causing the cartilage to degenerate. Then the joint surface is made up solely of bone (the cartilage having been worn away) leaving a bone-against-bone joint surface which is painful for the cat. The problem is that the body cannot renew the cartilage, and the body tries to repair the damage by increasing bone production which only serves to make the problem worse. Cats in general are very good at not showing pain and can suffer from HD without limping at all. Instead they may move more carefully or less than cats normally do, and may also avoid jumping. Cats with a mild degree of HD may not suffer at all.

Since January 2000 the Swedish Maine Coon Cat Club has kept a public register of hip radiographs. This register is since June 2010 administered by PawPeds. The recommendation is that all breeding cats should be tested for HD before being used in a breeding programme in order to minimise HD in the breed. The register is official and its purpose is to find the frequency of HD in the Maine Coon breed. The health programme collaborates with the veterinary Dr Lars Audell who is the leading specialist in this field in Sweden. He sends the evaluated radiographs and the test results to the HD registrar. The latter then keeps the radiographs and registers the result which will be available to the public 60 days after the cat owner has received the results. The result is forwarded to the cat owner as soon as PawPeds has received payment.

Other breeds than Maine Coons are also welcome to join in this health programme

As Hip Dysplasia is not only found in the Maine Coon breed, it might be of interest to know for other breeds that they also have the possibility to join in this health programme. It appears in most breeds to a greater or lesser extent. Once there is a certain number of evaluations available, it will be possible for the breeders of that breed to make more specific recommendations for their breed. The registry for other breeds will be kept by the same person as for the Maine Coons and the procedure is identical for the moment.

Recommendations for testing and breeding of the Maine Coon

The grading protocol under this system is as follows:

  • Normal: good hips, no anomalies
  • Borderline: not quite perfect structure, but not pronounced dysplastic
  • Grade 1: the mildest form of dysplasia
  • Grade 2: moderately affected hips
  • Grade 3: badly affected hips

We have been advised by geneticists not to make a too narrow a selection of the breeding stock at the beginning of the health programme. It would not be wise to exclude cats with HD entirely from breeding. Therefore we recommend today that cats with the test result "Grade 1" on the scale used in Sweden are not automatically excluded from breeding but should only be mated to cats with no sign of HD = "Normal".

Feline Hip Dysplasia is an inherited trait involving multiple gene pairs. Two cats with no sign of HD together can produce offspringthat develop HD. Two cats having HD can also produce kittens that do not develop HD. Therefore each generation of a breeding stock should be tested for HD in order to reduce the risk of developing HD.

Results and statistics from the health programme are published regularly. Here are some examples of the registry (2012):

                          Offspring from two       Offspring from two HD   
 Tested cats: 2988        parents with unknown     tested parents with     
                   	   hip status:              normal hip status:      
 Normal:    1902 (63.7%)  Normal:     650 (58.9%)  Normal:     454 (76.0%) 
 Borderline: 127  (4.3%)  Borderline:  43  (3.9%)  Borderline:  22  (3.7%) 
 Degree 1:   571 (19.1%)  Degree 1:   221 (20.0%)  Degree 1:    82 (13.7%) 
 Degree 2:   295  (9.9%)  Degree 2:   139 (12.6%)  Degree 2:    32  (5.4%) 
 Degree 3:    93  (3.1%)  Degree 3:    50  (4.5%)  Degree 3:     7  (1.2%) 

The number of HD tested cats and available results is still quite small but the development certainly looks promising. The statistics show very clearly that parents with a normal hip status in general produce offspring with better results than parents whose hip status is unknown.

Hip Radiographs

Information to the Cat Owner

Information to the Veterinary

Clubs presently participating in this health programme: