Arthritis
Arthritis therapies –
how do the conventional treatments stack up to the more natural ones?
by Shawn Messonnier, DVM

One day, Cathy noticed that her nine-year-old cat, Nathan, was limping on one front leg. Thinking he might have injured it jumping onto his favorite windowsill, she took him to the vet, who told her he had arthritis.

Lameness like Nathan’s is one of the most frequent reasons people with older animals seek veterinary care. While disorders such as bone cancer and nervous system damage can sometimes be a cause, in the majority of instances the culprit is arthritis, the most common musculoskeletal disorder in older dogs and cats. (For this article, the term arthritis will refer to “osteoarthritis”, also called degenerative joint disease, a condition in which the bone and cartilage are diseased. Rheumatoid arthritis, an immunological disorder very rare in companion animals, will not be covered.)

What is arthritis?
In my practice, almost all animals over the age of ten have some degree of cartilage degeneration. Arthritis technically means “inflammation of the joint”, and causes swelling, stiffness and pain. The knee, shoulder, ankle, elbow, vertebrae and hips are most often affected. Therapies seek to decrease the inf lammation; when possible, they should also slow down the disease’s progression, or actually help the joint heal.

The cause of arthritis is unknown, although chronic instability of the joint, along with normal wear and tear, lead to cartilage erosion, inflammation, and the destruction of underlying bone. In dogs, joint instability can result from genetics (as in the case of hip dysplasia) or chronic overexertion.

The cartilage covering the bones (the articular cartilage) lacks nerves, and can therefore undergo considerable damage before the surrounding tissues (joint capsule, bones, and ligaments) become inflamed, causing pain and lameness. Annual screening of the hips and spine, the joints most commonly affected with osteoarthritis, allows early diagnosis and treatment before irreversible cartilage damage occurs.

How arthritis progresses
Joint cartilage is made of cartilage cells (chondrocytes) and the surrounding tissue matrix, the major components of which are collagen (a type of protein), water, and proteoglycans. The proteoglycan molecule has a central core of protein with numerous side chains of glycosaminoglycans (GAGS). There are several different proteoglycan molecules in joint cartilage, including chondroitin sulfate (the predominant GAG) and keratan sulfate. Glucosamine, a popular treatment for osteoarthritis, is a precursor chemical necessary for GAG synthesis.

As the animal walks, runs and plays, a lot of stress is placed on all components of the joint. With years of wear and tear, the cartilage breaks down and arthritis develops. Over time, the chondrocytes are not able to synthesize enough proteoglycans to help the cartilage heal. As the chondrocytes become further damaged, chemicals are released that cause inflammation and further damage the cartilage. The underlying bone can also be damaged, and the animal may refuse to use the affected limb due to pain. This is the point at which guardians often seek veterinary care. Some animals at this stage can be helped with nutritional therapies that heal the joint, although in others the arthritis may be too advanced. The earlier the animal is diagnosed, the greater the chances for healing.

Conventional treatments
Most conventional therapies do a great job treating inflammation and pain, but rarely help the joint to heal. In some cases, over time, they actually cause more cartilage damage. The main class of drugs used to treat arthritis are non-steroidal anti-inflammatory medications (NSAIDS). For animals, these include Rimadyl, EtoGesic, and Metacam. While NSAIDS are extremely effective, they should not be used on a regular basis. Side effects (more commonly occurring in older animals, those taking other medications, and with the chronic use of NSAIDS) include liver disease/failure, kidney disease/failure, ulcers or perforations of the stomach and intestines (heart attack and stroke, recently reported in the media as side effects of NSAIDS use in people, have not been reported in companion animals to date). The best way to use NSAIDS, if they must be used at all, is to give them to the animal only on days when he seems particularly uncomfortable. Even then, the lowest effective dosage (which is usually much lower than the label dosage) should be used to minimize the risk of side effects.

Corticosteroids such as prednisone may be prescribed for arthritis. However, due to side effects (including cartilage damage, diabetes, and increased infections) they have no place in the long-term treatment of arthritis.

Surgery is often overlooked as an effective therapy for animals with arthritis. For some, it is really the only answer. While it cannot cure arthritis per se, it can replace defective anatomy. For example, a total hip replacement for a dog with bad hip dysplasia will solve the problem. Unfortunately, many arthritic animals are older and may not be suitable candidates for such involved surgery. Still, it is worth discussing the possibility with your veterinarian.

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Published in the June/July 2005 issue of Animal Wellness