Medications for Degenerative Arthritis
Degenerative joint disease is the number one cause of chronic pain in the dog and cat. The condition itself is the result of long-term stresses on a joint either as a result of old injury or of natural development of a poorly conformed joint in that individual. While surgery may be able to help in some situations, most of the time the degeneration of the joint cannot be reversed and treatment focuses on preventing progression of damage. Numerous products are available on the market; some are best combined with others and some cannot be combined. What we do know is that arthritis pain is best addressed by what is called a “multi-modal approach,” meaning that several approaches combined yield better results than any single therapy. The section presented here focuses on medications. Medications for arthritis pain are divided into two groups: Fast-Acting (Non-Steroidal Anti-Inflammatory Drugs and Cortisone-type Drugs) and Slow-Acting Drugs.
Slow-acting drugs of arthritis ultimately improve joint function and help with pain relief but they require a time frame of weeks to months to exert their effect. They may have disease-modifying properties such that their benefit continues even after their use has been curtailed. These products are typically what are called “nutriceuticals” meaning that they are nutritional supplements that have medicinal properties. Most arthritis patients can benefit from their use and they are considered a basic starting level for joint care.
GLUCOSAMINE AND CHONDROITIN SULFATE
These products are cartilage components harvested chiefly from sea mollusks (i.e., cartilage is made up of chondroitin sulfate and glucosamine metabolites, among other things). By taking these components orally, the patient is able to have plenty of the necessary “building blocks” needed to repair damaged cartilage. It is also felt that these products may have some anti-inflammatory properties separate from their structural uses. Unlike the anti-inflammatory medications described later on, these products do not produce rapid results; one to two months are needed for them to build up to adequate amounts. There are numerous products available combining glucosamine, chondroitin sulfate, assorted vitamins, creatine (a muscle “building block”), omega 3 fatty acids and more. Many “senior” diets or “joint supporting” diets, are well fortified with glucosamine.
OMEGA THREE FATTY ACIDS
It should be noted that the flax seed oil is readily converted to omega three fatty acids in the human body. This conversion is not so easy in the canine or feline body (only about 10% of the oil is converted). It is a waste to add flax seed oil to pet food; fish oils are needed. Numerous brands are available and the chances are your veterinarian stocks one. The appropriate dose is still somewhat controversial but the ratio of EPA (eicosapentanoic acid) to DHA (docosahexanoic acid) should be 3:2.
MSM stands for “methyl sulfonyl methane” and represents another “nutriceutical” anti-inflammatory agent. MSM is present in most plant and animal tissues and is a natural source of sulfur; however, for commercial sale MSM is derived from DMSO (dimethylsulfoxide), a solvent that comes in both medical grade and industrial grade. One might wonder why a sulfur source would be helpful in treating arthritis. The glycosaminoglycans that enable cartilage to soak up water and thus act as a cushion for articulating bones, are all sulfates. The idea with this product is to provide nutritional “building blocks” for cartilage repair. Beyond this, MSM seems to have anti-inflammatory properties and may act as an anti-oxidant (see below).
ANTI-OXIDANTS AND FREE RADICAL SCAVENGERS
Free radicals are harmful biochemicals that can attack us from external sources (such as pollution, sunlight, etc.) or we make them ourselves as by-products of oxygen use. These harmful little molecules are highly reactive and attack our structural proteins as well as cause production of assorted inflammatory proteins. One prominent theory of aging centers on free radicals with the idea that the damage free radicals cause to our brains, skin, joints etc. is the foundation of age-related debilitation. Normally, our bodies use natural anti-oxidants to inactivate free radicals; by supplementing with additional anti-oxidants, age-related change can be retarded.
Anti-oxidants that are readily available include Vitamin C, Vitamin E, SAMe, Superoxide Dismutase (S.O.D.) and others. Oxtrin® and Comfort Tabs® (S.O.D.) are marketed for joint support. Denosyl (SAMe) is marketed for animals primarily for its effects in the liver, though in humans its joint-related results are a primary focus. Hills produces a special anti-oxidant rich diet food called B/D diet, marketed mostly for its effects on the brain, but again, the anti-oxidants benefit all tissues, including joints.
NON-STEROIDAL ANTI-INFLAMMATORY DRUGS
Most pets with arthritis pain need relief now, not in 1-2 months when the cartilage building blocks and nutritional anti-inflammatories have had a chance to build up. The next mode of therapy is the NSAIDs, or non-steroidal anti-inflammatory drugs.
These medications act quickly by suppressing the inflammatory biochemicals that ultimately lead not only to the pain of arthritis but also to cartilage damage. None of these medications can safely be combined with one another. Further, human non-steroidal anti-inflammatories tend to be toxic to pets, especially cats. While aspirin has some potential use in relieving joint pain, safer medications developed specifically for pet use have become the standard for joint pain management. Never use a human medication of any kind in a pet without specific instructions on how to do so from your veterinarian.
Presently the following NSAIDs are available for pets:
These medications work by distinguishing between two prostagladin producing enzymes: cyclooxygenase I and cycloxoygenase II. Older drugs, such as aspirin, inhibited both forms of cycloxygenase alike which meant that they curtailed production of both inflammatory prostaglandins as well as “good” prostaglandins which help promote kidney circulation and intestinal health. Developing drugs that can distinguish between these enzymes has made it possible to develop safe anti-inflammatories for pets. Still, it is important to realize that classifying prostaglandins as “good” and “bad” is an oversimplification. Pre-treatment screening blood tests are still important before using an NSAID as a pre-existing kidney or liver compromise may preclude their use. Monitoring tests typically are recommended every six months for pets on NSAIDs.
The corticosteroid hormones (prednisone, dexamethasone, etc.) inhibit all production not only of prostaglandins but of leukotrienes as well. What this means in plain English is that these hormones create broad spectrum inflammation inhibition including wiping out some biochemical mediators it would be best not to wipe out. The result is relief from just about any type of inflammation: arthritis, itchy skin, immune-mediated disease and more, but in the long run side effects are problematic:
Using these medications to control arthritis pain is not desirable in the long term and one of the other medications mentioned would be a better idea.
ANALGESICS WHICH ARE NOT ANTI-INFLAMMATORY
Sometimes the combination of a cartilage protecting agent and an anti-inflammatory drug is not adequate for pain control. There are several appropriate pain relievers that can be used in pets. These medications are strictly analgesics and do not modify the inflammation in the joint.
The medications cat be used in cats and dogs alike and are compatible with all other the other medications listed. A synergism occurs when these medications are combined with NSAIDs such that the combination of both drugs produces greater results than one would expect.
In conclusion, the arthritic pet has a large menu of medications to select from and while proper medication is an important part of therapy, weight control and proper exercise should not be forgotten. Proper exercise is excellent physical therapy for the arthritic pet, as it is crucial to maintain as much muscle mass as possible to support the abnormal joint. Massage and gentle flexion/extension of the joint may also help. Remember, treatment for joint disease is likely to involve a combination of medications in addition to physical activities.
For more specific recommendations for your individual patient, please consult your veterinarian.
Page last updated: 3/13/09