Arthritis in dogs and cats just as in humans is an inflammation of any joint in the body. This inflammation can have many different causes.
The most common type of arthritis in dogs and cats is osteoarthritis. Osteoarthritis can be due to wear and tear on joints from over-use, aging, injury, or from an unstable joint such as what occurs with a ruptured ACL (anterior cruciate ligament) in the knee. The chronic form of arthritis in cats and dogs (and humans too) is called degenerative joint disease (DJD). It is estimated that 20% of dogs over one year of age have some form of DJD. One study showed that 90% of cats over 12 years of age had evidence of degenerative joint disease on x-rays. One of the problems with diagnosing feline arthritis is the natural feline tendency to be aloof and hence not complain about every ache and pain. So its up to the human to notice that Tabby just isn't jumping on the couch as well as before. Or there might be other subtle hints to watch for.
Another cause of this inflammation can be infection in the joints of dogs and cats. Septic arthritis is caused by a bacterial or fungal infection. Lyme disease or Ehrlichia can also cause arthritis. Autoimmune diseases, now known as immune-mediated diseases, such as lupus can cause swollen, painful, inflamed joints. More rarely, tumors can lead to arthritis.
Treatment for arthritis in dogs and cats should be directed to the inciting cause if possible. For example, surgery may be needed to stabilize a joint, or the infection is treated with medication.
Degenerative joint disease may be treated with non-steroidal anti-inflammatories (NSAIDS), pain medications like Tramadol, cartilage protective agents such as glucosamine, or Adequan.
NSAIDS come in many types and names. It is recommended to use NSAIDS developed specifically for pets, and not ones made for use in people. Human NSAIDS have a narrow margin of safety in dogs and, and are highly likely to cause ulcers in dogs. The majority of NSAIDS cannot be used in cats at all—the cat’s body is not able to metabolize NSAIDS, and so they become toxic very quickly. Cats should NEVER be given Tylenol as it can be fatal to them.
Occasionally, a dog will not be able to tolerate long term therapy of certain NSAIDS. So, before starting long-term therapy, we will usually recommend to check certain blood chemistries before starting the medication, and then rechecking after several weeks of therapy.