Hip Dysplasia in Cats
In this article on hip dysplasia in cats, I refer to a research study entitled, “Hip Dysplasia: A Feline Populations Study by GG Keller DVM MS et al, dated 1999 and published by Wiley InterScience. Short quotes that are permitted under license are from this paper.
Hip dysplasia is the abnormal development of the hipbone and the femur (coxofemoral joint).
Hip dysplasia affects many species including the human. It is the most “commonly diagnosed orthopedic disease in dogs.”
Hip dysplasia is inherited. The mode of inheritance is polygenic. The environment under which the cat lives can exacerbate the illness.
Cats “seldom have clinical signs referable to hip lameness”. The lack of obvious symptoms may have allowed breeders, who selectively breed for appearance, to include cats predisposed to hip dysplasia in their breeding programmes.
The Maine Coon cat, probably the world’s most popular purebred cat is known to suffer more than most breeds with this defect. The Orthopedic Foundation for Animals Inc. hip registry has records in relation to the Maine Coon that indicate that over the period Jan 1st 1974 to Dec 31st 1995 there were 288 requests for evaluation of “coxofemoral joint conformation in cats”. Of these 284 related to the Maine Coon (123 males and 161 females). 21.1% had “radiographic evidence” of hip dysplasia.
As to the study in question, x-rays of cats taken over the period Jan 1st 1991 to 31st December 1995 at the University of Missouri, Columbia College of Veterinary Medicine were screened.
696 cats were evaluated. 12 breeds were represented. This is well short, incidentally, of the 40 odd breeds recognised by the CFA. There are over 100 cat breeds in all. This is a limited survey but useful nonetheless.
The findings are as follows:
Hip Dysplasia in Cats – Conclusions
- The most consistent finding was a “shallow acetabulum”. “The study indicates that hip dysplasia in cats us consistently associated with an abnormally shallow acetabulum.” The head of the femur meets with the pelvis at the acetabulum, forming the hip joint. The acetabulum is the socket element of the ball and socket joint that is the hip joint.
- There was no significant difference between female and male cat.
- The incidence of hip dysplasia in cats may be higher in certain purebred cats than others. The chart shows higher frequencies in Himalayans (pointed Persian) and Persians. The incidence levels were similar for random bred and purebred cats.
- The increased incidence of hip dysplasia in cats in relation to Persians may be linked to their larger than average size (as is the case with the Maine Coon). My comment: but there are other large cats that seem not to be linked to hip dysplasia.
- Another possible reason for a higher level of affliction is a “narrower base gene pool” (inbreeding).
- Larger studies need to take place (my comment: has this happened?)
- Breeders should evaluate the cats in their stock (my comment: I am sure that many breeders especially of the Persians and Maine Coon do this). “Selective breeding based on normal phenotype will reduce the frequency of hip dysplasia in cats” over time. In layman’s terms this means breeding from cats that do not have hip dysplasia will gradually eradicate the condition (my comment: is there a coordinated programme amongst MC and Persian breeders and are breeders overlooking this problem to enhance the cat’s appearance?)
Photo: taken 2005 April 13th. This cat, “Squeaker”, had problems with hip dysplasia. She was 10 years old at the time. Photo by satragon (Flickr name of cats human companion).