Osteoarthritis in Cats: A More Common Disease Than You Might Expect

     With all those bones, you can imagine that cats suffer from joint problems, also.

     Arthritis in cats is the most under recognized problem in cats.

     It’s reported that 90% of all cats over the age of 12 have arthritis, so see your veterinarian if your cat’s activity level or sleep patterns have changed!

Thanks to the marvels of modern veterinary medicine, our pets are living much longer lives. With longer lives, however, come chronic diseases such as osteoarthritis. Osteoarthritis is a commonly recognized disease in dogs. However, it is now being recognized as a disease of geriatric cats.

Osteoarthritis is a degenerative condition of the joints in which the normal cartilage cushion in the joint breaks down. Eventually, adjacent bones rub against each other, causing pain, decreased joint movement, and sometimes the formation of bone spurs and other changes around the joint.¹ Osteoarthritis is a progressive disease; however, it can be actively managed so that the course of the disease is slowed and remaining joint function is preserved.

Physical diagnosis of osteoarthritis in cats is difficult even for experienced veterinarians. Cats, unlike most dogs, can tolerate severe orthopedic disease due to their small size and natural agility. Cats generally resent being physically handled or manipulated during clinical examinations. Thus, the examining veterinarian may have difficulty in determining whether a cat is pulling its foot away because of pain or simply because it doesn’t want to be touched.  Cats are also notorious for cowering on the examination table and remaining immobile. Due to these obstacles in diagnosing osteoarthritis in cats, veterinarians will often simply rely on the cat owner’s observations that their pet is not moving around as well as it once did. Veterinarians will rule out osteoarthritis as a diagnosis by actually having the owners treat the cat for osteoarthritis and seeing if the owners note any improvement in their cat’s quality of life.

Changes to osteoarthritis-affected joints in cats are usually subtle. Decreased range of joint motion, commonly seen in dogs, is uncommon in cats. Crepitus, a grinding/crunching sound or feeling in a joint, is also common in dogs, but uncommon in cats. Thickening of the tissues surrounding affected joints, however, is a common finding. .

Clinical signs of osteoarthritis in cats include weight loss, loss of appetite, depression, change in general attitude, poor grooming habits, urination or defecation outside the litter pan, and inability to jump on and off objects. Surprisingly, lameness is not as commonly reported a clinical sign by owners as one would expect. Because joints are frequently bilaterally affected (meaning that if one elbow is affected, the other elbow is also affected), cats can compensate and appear to be walking normally.

The most frequently affected joints in cats are the elbows and hips, although shoulders and hocks have also been reported. Interestingly, arthritis of the vertebrae and sternum (the axial skeleton) is also common. In one study, 74 of 218 cats were diagnosed with osteoarthritis. Of the 74 cats, 21 (28.4 percent) had osteoarthritis in the limbs and the vertebrae, 24 (32.4 percent) had osteoarthritis in the vertebrae only, and 29 (39.2 percent) had osteoarthritis in the limbs only.

Several studies have been conducted evaluating radiographic changes associated with osteoarthritis in cats. less severe than those observed in dogs with osteoarthritis. In many cases, cats with osteoarthritis have no radiographic changes. In an ongoing feline osteoarthritis study by world-renown veterinary pain expert, B. Duncan X. Lascelles, Assistant Professor of Small Animal Surgery at the North Carolina State University School of Veterinary Medicine, where he also directs the school’s Integrated Pain Management Service, 73 percent of enrolled cats had evidence of osteoarthritis on radiographs. The radiographic changes noted in the study were mild, but when the affected joints were examined at necropsy, significant cartilage loss was found. Thus, radiographic changes in cats, if present, may not correspond to the degree of osteoarthritis present in the joints.  Painful joints did not necessarily correspond to radiographic findings.

Treatment options for cats with osteoarthritis are limited. Non-pharmaceutical treatment options include weight loss for overweight cats, increased exercise, and environmental accommodations (e.g., using litter pans with lower sides for ease of entering and exiting, and elevating food and water bowls, and providing soft bedding). With regard to pain relief, steroids have been used in the past; however, they have fallen out of favour due to side effects. No NSAID is currently approved for safe, long-term control of osteoarthritis pain in cats.

Development of pain assessment tool

Pain in animals, particularly cats, is difficult to assess, and there are few validated pain assessment tools. Researchers, including Dr. Lascelles, are trying to develop more “objective” tools for pain assessment to greatly decrease personal bias. Currently used objective tools include force plate analysis (measures the amount of force a limb generates at one instant in time) and pressure-sensitive walkways (that indirectly measure the amount of force generated at one moment in time).

Conclusion

Diagnosis of osteoarthritis in cats is difficult even for the experienced veterinarian. Thus the disease remains largely underdiagnosed and undertreated. However, as new methods of pain assessment are developed, osteoarthritis in cats may soon become a readily recognized and actively managed disease, thus alleviating the silent suffering of many geriatric cats.