The most common signs of arthritis and joint disease in cats include stiffness, limping, or favoring a limb – particularly after sleep or resting, reluctance to jump or even climb stairs, and noticeable pain.
As in dogs, there are many causes of arthritis and joint disease in cats. These include trauma, infections, immune system disorders, and developmental disorders such as hip dysplasia (yes, cats can get hip dysplasia).
In the following article we will discuss some of these causes or conditions which are more common or unique to cats. Before you read on, you may want to check out the articles Joint Anatomy and Veterinary Procedures Used to Diagnose Joint Disease for some background information. Information on how to manage cats with arthritis and other joint problems, including the use of Glucosamine and Chondroitin is discussed in Treatment of Osteoarthritis in Cats.
Feline progressive polyarthritis, as the name suggests, affects multiple joints in a cat and worsens over time. There are generally two types of this disease.
In the first type of progressive polyarthritis, the cartilage is eroded from the ends of the bones making up the joint and bony spurs and bone thickening occur in bones adjacent to the joint. These kinds of changes are similar to those seen in hip dysplasia and other degenerative joint disease. The most commonly affected joints are those of the feet, the carpus (wrist), and hock.
In the second type of progressive polyarthritis, the erosion of the cartilage is severe such that the bone under the cartilage is exposed, which causes severe pain. This is similar to rheumatoid arthritis in dogs and people.
Regardless of type, progressive polyarthritis in cats generally affects young and middle-aged male cats (neutering appears to make no difference). The cats show a reluctance to walk, the joints are swollen, the range of motion is reduced, and in some cases, the cats experience recurring episodes of fever, loss of appetite, and swollen lymph nodes.
There is no cure for either type of progressive polyarthritis. Even with strong combinations of pain relievers, anti-inflammatories such as prednisone, and more potent medications, which suppress the immune system, many cats remain in extreme pain and owners may elect to have the cat euthanized.
Arthritis caused by calicivirus infection
Calicivirus is a virus that is most well-known for the respiratory disease (usually runny eyes and nose) it causes. Calicivirus is often included in the distemper-rhinotracheitis-chlamydia vaccine, which is given to kittens and cats.
In addition to respiratory disease, calicivirus can cause inflammation in the joints, which results in lameness. This condition has been associated with both the field strain (the strain which generally causes disease), and rarely, the vaccine strain. Respiratory symptoms may or may not be present along with the lameness. The cats with calicivirus-associated lameness often develop a fever and may be reluctant to eat.
It is generally a self-limiting disease, which means it usually resolves on its own. Supportive therapy such as pain relievers and anti-inflammatory medication is sometimes given. The vast majority of cats fully recover.
Rarely, cats with diabetes mellitus (sugar diabetes) develop an unusual gait in which the hocks touch the ground when the cat walks. This is thought to be related to a disorder of the nerves, but can be mistaken for a joint problem.
In cats, joints most often become infected as a result of bite wounds. The joint becomes swollen, painful, warm to the touch, and the cat will often not want to bear any weight on the affected leg. The cat often has a fever and will not eat. At times, the infection can spread from the joint to the bone (bone infection is termed 'osteomyelitis').
Treatment involves draining the infected joint fluid from the joint, flushing the joint, and placing the cat on antibiotics. Because bacterial infections of the joint can rapidly produce permanent injury to the joint, infectious arthritis must be treated as soon as it is detected.
Other joint diseases
Several other joint conditions which are more common in dogs do occur rarely in cats. These include degenerative joint disease (osteoarthritis), ruptured anterior cruciate ligament, luxating patella, hip dysplasia, (intervertebral) disc disease, and hyperparathyroidism.