The U.S. cat population is aging. In the last 10 years, the percentage of cats over 6 years of age has grown from 24 percent to 47 percent, the percentage over 10 years of age has grown 15 percent, and the percentage over 15 years of age from 5 percent to 14 percent.
As the cat population ages, there is an increasing awareness that they are affected by osteoarthritis (OA) just like dogs and other species. This recognition is important because traditionally it has been assumed that cats do not suffer from OA, mainly because cats generally don’t show lameness like dogs. However, it is now clear that cats are affected by OA.
Over 90 percent of cats over 12 years of age are reportedly affected. Instead of lameness, affected cats show their chronic pain through changes in lifestyle and behavior, including loss of appetite, weight loss, poor grooming habits, urination or defecation outside the litter box, reluctance or inability to jump on or off objects, change in attitude, irritability when handled and prolonged sleeping.
OA is a progressive, degenerative condition affecting joints. The cause and contributing factors in cats are poorly understood. Over time, the normal cartilage in the joints breaks down; pain results from inflammation, bone on bone contact, formation of bone spurs, and other degenerative changes affecting the joints and surrounding tissues. The most commonly affected joints are the elbows and hips; however, shoulders and hocks are also reported. Significant numbers of cats have OA involving the spine and sternum. Since OA is a progressive problem, it should be actively managed with the goal of slowing progression, preserving remaining joint function, and maintaining quality of life.
Interestingly, OA in cats can be difficult to diagnose even for experienced veterinarians. Cats appear to be very tolerant of severe joint disease because of their small body size and normal agility. Diagnosis is complicated by the fact that most cats do not like to be examined and generally do not walk around the veterinarian’s examination room. In addition, the degenerative changes associated with OA in cats are subtle. Obvious reduced joint range of motion and crepitus (grinding or crunching) are uncommon in the cat. Thickening of the tissue around the joints is common in cats, but the extent is not always easy to completely appreciate. X-rays can be valuable, but a large number of cats with OA associated pain do not show OA changes on X-rays. As a result of these challenges, the owner observations at home are essential for alerting the veterinarian that there is a potential OA problem.
Treatment options have been limited, due primarily to a lack of research focused on cat OA. Information from dogs and other species cannot be easily or reliable extrapolated to cats because cats metabolize drugs differently and the causative factors leading to OA are unclear. Management methods include using litter boxes with lower sides for ease of entry and exit, elevating the food and water bowls to reduce the amount of bending during feeding, providing soft bedding to increase comfort, reducing or eliminating the need to jump up on the sofa, windowsill or other favored location through the use of a ramp or series of small steps, and spending time grooming the cat.
Some authorities recommend the long term use of specific non-steroidal anti-inflammatory drugs (NSAID) based on their use outside the U.S. As with all NSAID drugs, there is the potential for side-effects that may involve the stomach and intestines, kidneys, heart, or liver, especially in cats. A complete evaluation and discussion with a veterinarian should occur before initiating any NSAID therapy. Supportive therapies that have been shown to increase activity of cats with OA include diets high in glucosamine/chondroitin, green-lipped mussel extract, and fish oil. Acupuncture can be a valuable addition to the support plan. For pain not effectively managed by these options, drugs like buprenorphine, gabapentin, tramadol, and amantadine have been advocated.
Since pain is difficult to assess in cats, determination of response to therapy is based on owner observations, such as increased mobility, increased activity levels, improvements in appetite and return to previously normal behaviors. Therefore, close communication between the veterinarian and the cat owner is essential for optimal management of OA in cats.
If you suspect your cat has OA, contact your veterinarian so that a complete discussion, evaluation, and comprehensive plan for therapy can be developed. Slowing the progression of OA and managing any associated pain can improve the quality of life for your cat companion.
Ron Carsten, DVM, PhD, CVA was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. In addition to his Doctor of Veterinary Medicine, he holds a PhD in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist. He practices integrative veterinary medicine in Glenwood Springs.