Hip dysplasia is an uncommon, painful and degenerative disease that causes arthritis-like symptoms and general hind end lameness. It is caused by a combination of genetic and environmental factors that lead to laxity (looseness) in one or both hip joints. Diagnosing this disorder can be difficult, because a number of other diseases cause similar clinical signs and must be ruled out before a definitive diagnosis of hip dysplasia can be made.
Diagnosing Hip Dysplasia in Cats
If a cat presents with unilateral or bilateral hind end lameness – especially if it is either an older kitten or an aging adult - the initial veterinary database normally will include blood work (complete blood count and serum chemistry panel run on fresh blood samples), a urinalysis, palpation of the hip joints (this may require sedation or even general anesthesia because of pain) and pelvic radiographs (x-rays). Very specific positioning of the animal for hip radiographs is essential to an accurate diagnosis of hip dysplasia.
There are several ways to detect hip dysplasia, whether or not clinical signs are present. This is important because some breeders may wish to have their cats tested before breeding them. The older and more common method is recommended by the Orthopedic Foundation for Animals (the OFA), which will assess the hips of cats under the same rules, guidelines and fee schedules applicable to dogs. The cat’s veterinarian will take radiographs of the hips with the cat in a specific stretched-out position – on its back, with its hind legs pulled back and slightly rotated – and will submit those films to the OFA. There, specialized veterinary radiologists will analyze the radiographs and compare them to a large computerized database of hip x-rays of other cats to determine whether hip laxity exists and, if it does, how severe it is at that point. While this can be done in young cats, the accuracy of this method is much greater if the cat is over 2 years of age when the films are taken.
The other recognized method, called PennHip, is currently only available for assessing canine, not feline, hip dysplasia.
Confirmatory testing might include additional x-rays taken at different views and possibly computed tomography (CT or CAT scan).
Basically, your general veterinarian, perhaps in consultation with a veterinary radiologist, will be able to diagnose whether your cat is affected by hip dysplasia. Whether it is an older cat showing significant symptoms, or a younger cat without clinical signs, there are medical and possibly surgical options available to treat or at least manage this disease in companion cats.