Arthritis
By Dr. Karen Thomas

A moveable joint at the intersection of two or more bones is held together by a joint capsule and ligaments. It is cushioned by cartilage on the bone ends and lubricated by joint fluids. Arthritis occurs when any of these components break down. Although old age wear and tear is probably the most common cause, there are many others. Infectious causes include bacteria which reach the joints by way of bite wounds or other punctures and those that arrive by way of the blood such as Borrelia (Lymes Disease) and “joint ill” from the umbilicus in new born puppies, kittens and foals. Fungal infections may also be seen in joints. Immune mediated joint disease such as rhematoid arthritis is uncommon but is the first diagnosis considered when multiple joints are suddenly affected by swelling and pain.

Some veterinarians consider Lymes arthritis to be an immune mediated after effect of Borrelia infection as opposed to being caused by the infection itself. Ruptured cruciate ligament of the knee is a common injury in middle aged overweight dogs. Because it occurs with minimal trauma in dogs, investigations are underway to determine if there may be an immune component to this ailment. Infectious and immune mediated joint disorders are suggested by the presence of fever, swelling in one or more joints, and severe lameness or reluctance to move. The diagnosis is based on blood tests, xrays, and laboratory examination of joint fluid. In rare cases a biopsy may be necessary. Appropriate treatment—antibiotics or steroids--may cure or control these conditions but unless diagnosis and treatment happen early there may be permanent joint damage and arthritis later in life. Any moveable joint can be affected by traumatic dislocation, but the hip is the most frequently involved. Sometimes dislocations can be replaced under anesthesia by simple manipulation, but often surgery is needed to reduce luxations, and pins or screws may have to be used to hold the joint together.

Surgery is also a treatment option for some joints which develop improperly during growth. Once again the hip is the joint most likely to be affected. But besides hip dysplasia, there are a number of other congenital or developmental joint disorders. Lack of fusion of growth centers in elbows causes an ununited anconeal process or fragmented coronoid processes called “elbow dysplasia”. Uneven bone growth called osteochondritis dessicans (OCD) occurs most often in the shoulders but may be seen in many other joints. It can lead to broken off pieces of cartilage which calcify in the joint. These joint “mice” feel to the dog like a rock in your shoe. A circulatory disorder in the hip of toy dogs causes severe hip deformation called Legge-Perthes syndrome. The knee joint is very complex with three major bones—the femur, tibia, and fibula; and three minor bones—two fabellae and the patella. Growth deformities, especially related to displaced or dislocating patellas, are common.

Since early detection and treatment of joint disorders delays progression of arthritis and prevents a great deal of discomfort it is important to ask your veterinarian about the appropriate time to evaluate your puppy for joint disease. Palpation and/or xrays can detect problems before lameness begins. Persistent or recurrent limping, an unusual gait or poor muscle development in young growing dogs should be investigated. If early arthritis or its predisposition can be detected there are several things that can be done. Whenever possible, surgical correction of the defect should be performed.

Cost on these operations ranges from several hundred to a few thousand dollars depending on the type of operation. There are several different types of operations available for hip dysplasia and knee deformities. Most should be performed by a specialist or at a university but some may be performed by a general practice veterinarian. Such surgery on a 4-8 month old dog can buy years of pain free existence.

If surgery is not an option, keeping the dog thin and providing daily exercise are very helpful. Exercise should be walking or swimming daily, not chasing a frisbee on weekends and being a couch potato all week. (Does this sound like advice our doctors give us?)

Chondroprotective agents (chondro=cartilage) can be used lifelong. These include adequan, an injectable drug given once a month, and glucosamine with or without chondroitin. Glucosamines are oral “neutraceuticals” sold as food supplements, not FDA approved drugs. Their usefulness has been shown by years of experience as opposed to controlled drug trials. Because there are many brands and their production is not regulated, it is important to check with a veterinarian to make sure you get one with the proper strength, dose and purity.

Chondroprotectives strengthen and heal cartilage and improve the lubricating ability of the joint fluid. They can be used even in cases where arthritis is quite advanced but for improvement to occur they should be given in high doses for a short induction period followed by a lower maintenance dose.

Another option for more advanced cases is non steroidal anti inflammatory drugs (NSAIDS). This family includes aspirin, phenylbutazone (a horse medication), and ibuprophen. The two NSAIDS which are approved for dogs at this time are Rimadyla and Etogesica. Unlike human drugs, they have been shown to be generally safe when given over a long period of time, and their direct pain relieving effects make them especially useful for more immediate relief. Your veterinarian may advise periodic monitoring for signs of stomach ulcers or liver disease as these may occur in very rare cases with these drugs.

Accupuncture has been used to relieve chronic arthritic pain, but it should be performed only by someone trained and experienced in its use. There are other supplements such as super oxide dismutase, a free radical scavenger, which may be of use in selected cases.

A special note to cat owners. Although cats are less likely to develop arthritis than dogs, bite wounds and other traumatic joint injuries do occur. Both hip dysplasia and knee cap luxations have also been seen in cats. In addition, cats are now living longer, and are more inclined to be overweight, so we can expect to see an increase in arthritis in senior cats.

There are currently no NSAIDS which are safe for use in cats. Neither tylenol (acetaminophen), nor aspirin nor either of the new dog NSAIDS should be used for arthritis in cats. The chondroprotectives are safe in cats but there is less data to demonstrate effectiveness. The simple application of heat by way of heating pads or hot compresses can temporarily relieve discomfort.

If you know your pet is arthritic, do not assume that it doesn’t hurt if it is not limping. The gradual onset of arthritis pain accustoms the pet to higher and higher levels of discomfort. If two or more legs are equally bad it is impossible to limp on one leg without making another leg hurt worse. Look for general stiffness, reluctance to use stairs, lameness that improves as the animal moves around, and muscle atrophy. Many owners of older pets are pleasantly surprised at how much more active the pet becomes when arthritis treatment is begun.