Until very recently, cats were not thought to be affected by hip dysplasia. Well known in many dog breeds as an inherited disorder, cats were felt to be free of the condition. New information and research has shown that this disease does indeed exist in cats and is likely an inherited disorder.

Hip dysplasia is not caused by one single gene. It is a polygenitic, complex disease, caused by several genes. The disease is not congenital (meaning that an animal is not born with it) but rather develops over a period of time, resulting from instability in the ball and socket portion of the hip joint. Abnormal hip joint laxity—looseness between the femoral head, the ball, and the acetabulum, the socket—is the initiating factor that results in the condition known as hip dysplasia.

The looseness that occurs within the joint contributes to secondary changes. A major change is the deterioration of the articular cartilage (articular cartilage functions as a lubricating mechanism within the joint). The degenerative changes that occur within the joint cause the femoral head and acetabulum (the ball and socket) to rub together and with every step, causes the cat to experience pain. Eventually, as the condition progresses, the cat develops severe degenerative joint disease (osteoarthritis) of the hip.

Symptoms of feline hip dysplasia are somewhat similar to symptoms of canine hip dyspalsia. Severely affected cats have obvious symptoms and experience pain. These cats may appear to be stiff when they walk, walk with a pronounced limp, and may be reluctant to jump or climb. Cats that are moderately affected appear less lame or lame from time to time. In some cases, the symptoms only appear after some traumatic event, such as a fall. Other cats totally mask the symptoms of hip dysplasia and appear normal.

Hip dysplasia is a condition which is present in the general feline population (in the random-bred, general cat population as well as in purebred cats) and is seen in all types of body styles—from relatively small cats like the Siamese to the larger breeds like Persians and Maine Coon Cats.

In the case of purebred cats, the breeders determine which cats can breed. Current thinking suggests that the greatest impact on reducing feline hip dysplasia can be made by breeders who choose to breed only cats that have been evaluated for the presence of hip dysplasia.

Diagnosis of feline hip dysplasia is made by x-raying the affected cat’s hips. Currently there are two different methods for evaluating hips. The most widely used method is that of the Orthopedic Foundation For Animals (OFA). The other method is done in conjunction with the University of Pennsylvania and is called the Penn Hip Improvement Program (PennHIP).

The OFA method is readily available as X-rays are taken by your local veterinarian and then forwarded to the OFA for evaluation. The PennHIP method for felines is currently available only via the University of Pennsylvania. While both utilize radiographs, the methods vary as do the opinions on which method is best.

Selective breeding is the key for reducing the incidence of feline hip dysplasia. Only cats that have sound hips, with no radiographic signs of hip dysplasia, should be used for breeding. Cats with radiographic signs of hip dysplasia should not be used for breeding and should be neutered at the appropriate age.