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 collaborated with the veterinary Dr Lars Audell, who is the leading specialist in this field in Sweden, during the setup and the first 15 years of evaluations. From February 2020 Elisabeth Ball evaluates the radiographs. The evaluated radiographs and the test results are sent to PawPeds. The results will then be available to the public 60 days after the cat owner has received them. The result is send 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
  • Grade 1: the mildest form of dysplasia
  • Grade 2: moderately affected hips
  • Grade 3: badly affected hips

Earlier there was also a grade "Borderline" for not quite perfect structure, but not pronounced dysplastic. This grade is not used since July 2013.

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 the health program 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 sometimes published. Here are some examples of the registry (2018):

Offsprings HD-status (worst hip) based on parents status (worst hip). Total number of evaluated cats: 4263
                N x N    N x 1    1 x 1    2 x 2    U x U   
                (n=949)  (n=505)  (n=57)   (n=4)    (n=1662)
 Normal (N):   76.7%    62.2%    50.9%    25.0%    57.8%   
 Grade 1 (1):  14.1%    24.8%    24.6%    50.5%    21.1%   
 Grade 2 (2):   5.4%     8.9%    15.8%    25.0%    13.3%   
 Grade 3 (3):   1.9%     1.6%     1.8%      ---    5.4%    

                N x N    N x 1    N x 2    N x 3    
                (n=949)  (n=505)  (n=68)   (n=18)  
 Normal (N):   76.7%    62.2%    55.9%    50.0%   
 Grade 1 (1):  14.1%    24.8%    17.6%    16.7%   
 Grade 2 (2):   5.4%     8.9%    13.2%     5.6%   
 Grade 3 (3):   1.9%     1.6%     2.9%     5.6%   

The number of HD tested cats and available results indicate that the development certainly looks promising. The statistics show very clearly that parents with a normal hip status (N) in general produce offspring with better results than parents whose hip status is unknown (U).

A scientific study of the HD results in the health program was published in 2019. There you will find a more thorough analysis of the statistics and the results of the health program.

Hip Radiographs

Information to the Cat Owner

Information to the Veterinary

Clubs presently participating in this health programme: