Ask Dr. Richards: 07/06

My best friends cat has just been diagnosed with hip dysplasia, and Im really surprised. One of my dogs had the disease (and I know she suffered a lot from arthritis in her hips as she got older), but I didnt know cats could get it too. Is it common?

Feline hip dysplasia (FHD) hasnt received a lot of attention up to this point, even though the condition was first described back in the 1960s. The prevalence of the condition is not known with certainty, although reports suggest that its more common than previously believed. One study demonstrated that nearly seven percent of 700 cats evaluated had signs of hip dysplasia on X-rays. Its possible that the condition is more likely to appear in some pedigreed cat breeds. Thankfully, most cats with the disease dont appear to be bothered by it in the least, and in fact FHD is typically diagnosed only when X-rays are taken for some other reason.

Genetic factors are extremely important in the development of the condition in dogs; the same is probably true in cats, too. Many genes are involved in the expression of the disease, but nongenetic factors also play an important role in canine HD. The dogs rate of growth, body size and weight, nutrition and hormonal influences are all examples. For various reasons, in neither species is it yet possible to reliably control the disease through selective breeding alone – for example, by only breeding apparently unaffected individuals.

Most scientists believe that the initiating event in both canine hip dysplasia and feline hip dysplasia is excessive laxity in the hip joint, which then leads to damage of the joint cartilage and underlying bone. Degenerative joint disease is the ultimate consequence. But unlike their canine counterparts, most cats with hip dysplasia dont seem to be bothered by the condition. This may be because cats are small contrasted with dogs or perhaps because their hip joints are anatomically different from canine joints and may be better able to handle the laxity. Or they may simply be more tolerant of degenerative joint disease. (A dog-preferring friend of mine commented – with a wink – that cats dont do anything but lie around anyway, so how would one know that the cat had arthritis? I gently set him straight.) The rare cat that is experiencing difficulty may demonstrate a reluctance to jump or to climb stairs, be lame on occasion, have a hunched appearance when walking or appear to be in pain when assuming the urination/defecation posture. Needless to say, many other feline conditions can cause similar signs.

When a cat with hip dysplasia does require treatment, there arent many options. Weight loss will probably help obese cats, simply to relieve some of the extra stress on the joint. Medications are sometimes recommended, but rarely are they completely successful, and nontraditional therapies and nutraceuticals remain largely untested. Thanksfully, however, a surgical procedure, femoral head and neck ostectomy, produces excellent results in most cats, and it usually renders them pain-free and returns the hip joints – and the kitties – to near-normal function.


A friend of mine gave what she thought would be the right dosage of Tylenol to her cat, but within a few hours her cat was deathly ill and almost died. Why did this happen? Did she give too much?

Your friend did something we tell cat owners never to do. Never, never, never give a medication, even one that you think is safe, to a cat without first consulting your veterinarian. Although safe in humans, acetaminophen, the active ingredient in Tylenol, is highly toxic to cats; there is no safe dosage.

Even though many cat owners are aware of the danger of acetaminophen (also known as paracetamol in Britain; phenacetin is another source of acetaminophen), its easy to forget that it is often included in many other over-the-counter medications. In fact, its the major ingredient in most aspirin-free pain relievers and cold remedies. Because cats are so very much different from humans in the way they handle medications – not even mentioning the huge difference in size – a veterinarian should always be consulted before any medication is given to a cat.

Always make sure to inform the veterinarian of any other drugs present in combination products youre inquiring about giving to your cat. Granted, some commonly used human drugs can be safely administered to cats for certain conditions, but the dosage amount and frequency of administration often differ considerably for cats. I again emphasize, never ever (dont even think about it!) medicate a cat unless your veterinarian directs you to do so.