Hip Dysplasia

Hip dysplasia is far better known in dogs, but it occurs in cats too and is almost certainly under-diagnosed, because cats are experts at concealing lameness. Rather than limping obviously, an affected cat tends to simply do less — jumping up less often, choosing lower perches, moving stiffly, and quietly withdrawing from play. Owners frequently put these changes down to the cat 'getting older' when in fact a painful joint is to blame.

The hip is a ball-and-socket joint: the rounded head of the thigh bone (femur) should sit snugly in a cupped socket in the pelvis. In hip dysplasia the socket is too shallow or the fit is loose, so the joint is unstable. Every step lets the joint move abnormally, grinding and wearing the smooth cartilage. The body responds with inflammation and, over months to years, lays down the extra bone and scar tissue of osteoarthritis. The result is a joint that is progressively stiffer and more painful.

Genetics are the main driver, which is why the condition clusters in particular breeds. Large, heavy cats put more load through the joint, so Maine Coons are the classic example, with Persians and Devon Rex also over-represented. Excess body weight dramatically increases the strain, and it is one of the very few risk factors an owner can directly control.

Diagnosis rests on a careful physical examination — checking for pain, reduced range of motion and wasting of the hip muscles — confirmed by X-rays that reveal the poorly formed joint and any arthritis. The good news is that most cats do not need surgery. A combination of keeping the cat slim, providing joint-friendly nutrition and supplements, using vet-prescribed pain relief, and adapting the home with ramps, steps and easy-access litter trays keeps the great majority comfortable and active for years. Where pain cannot be controlled medically, surgical options such as removing the head of the femur (an FHO) reliably relieve the discomfort, and cats typically do remarkably well afterwards.