Although osteoarthritis is a significant condition affecting older cats, it can be difficult to diagnose. Some cats may be lame, but inactivity and disability without lameness are common. Frequently, more than one joint is involved; elbows and hips are most commonly affected. Radiography is useful in determining if presenting signs are caused by joint disease versus muscular or systemic disease. However, owners may be reluctant to allow radiography, especially if the cat is presenting for an unrelated concern. Thus, an NSAID trial may be reasonable. Because NSAIDs have numerous potential side effects, they should be avoided in cats with dehydration, GI signs, liver disease, or kidney failure. Hematology, biochemistry, and urine analysis should be conducted before the trial is initiated. The owner should be asked to focus on a few behaviors they think they can easily reassess to evaluate efficacy of the NSAID trial (eg, number of times the cat jumps onto a particular raised surface, increased use of the litter box, or decreased signs of lameness). While response to NSAID therapy is useful, it does not definitively diagnose osteoarthritis but is supportive evidence. In many cases, older cats will have concurrent diseases that must be taken into consideration and addressed.

Commentary
Pet owners may think that they have finally trained the cat not to jump up on the kitchen counter, but in actuality the cat may be in too much pain to jump. The unfortunate fact is many cats with osteoarthritis are not being diagnosed. This article is a good review of differentials, diagnostic tips, and treatment recommendations. We can make these older cats feel better, even if they do jump on that counter.—Patricia Thomblison, DVM, MS

Source
Companion animal practice: Diagnosis and management of osteoarthritis in cats. Godfrey D. IN PRACT 33:380-385, 2011.