MEDICATIONS FOR THE TREATMENT OF 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 and instability of a joint either as a result of old injury or of natural development of the 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.  The following is a summary of options:

Medications for arthritis pain are divided into two groups: Fast-Acting (Non-Steroidal Anti-Inflammatory Drugs and Cortisone-type Drugs) and Slow-Acting Drugs.

FAST-ACTING DRUGS (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.

ASPIRIN

Pala-Tech brand aspirin for dogs

Aspirin is a “non-steroidal anti-inflammatory drug” or NSAID. It is effective in relieving pain due to inflammation as is occurring within the arthritic joint. It has the advantage of being readily available and inexpensive. In some animals, however, it is simply not strong enough or it causes unpleasant side effects such as upset stomach or even intestinal bleeding. Aspirin also appears to inhibit the production of cartilage matrix by cartilage cells, which in the long run is not conducive to a healthy cartilage surface. Aspirin also deactivates platelets (the blood cell responsible for clotting) and thus can promote bleeding should surgery or trauma occur.
 

• Dogs can use aspirin up to three times daily. Cats, however, metabolize aspirin extremely slowly and require a very low dose and a typical dosing schedule of twice a week usage, which usually works out to be inadequate for pain management.
   
• Because this medication is available in almost every pet-owning household, there may be a temptation to guess a dose based on the human dose.  Do not be tempted to do this. Do not use aspirin or any other medication in your pet without veterinary guidance.
   
• Enteric coating of aspirin has become popular in human products. This coating is a problem in animals and creates unpredictable absorption. This becomes dangerous when enteric coated aspirin tablets do not digest in the stomach and instead collect in the stomach until a toxic dose is reached.  To avoid this disaster, use either aspirin made specifically for pets or aspirin with a powdery covering rather than the “hard candy” type enteric coating.

Overall, aspirin use in pets is associated with enough problems to make it a second choice.

For more information on aspirin click here.

RIMADYL (Carprofen) AND ETOGESIC (Etodolac)

These medications are also NSAIDs. They were developed as an improvement upon aspirin and other NSAIDs developed for humans for which side effects have been problematic in animals. Rimadyl and Etogesic are both designed for indefinite use in dogs with minimal side effect potential.  Both Rimadyl and Etogesic may be given once daily (the Rimadyl dose can be divided in two and given twice a day if desired).  Typically a short trial of one of these is prescribed to see if the effect is worth continuing; as with people, some individuals respond better to different NSAIDs. If the effect is good, then the medication can be continued.  Some blood testing is recommended prior to long term use and every 6 months thereafter.

• Approximately one dog in 5000 will have a serious liver reaction to Rimadyl. Animals with histories of elevated liver enzymes, pre-existing liver disease, Cushing’s disease, or phenobarbital use should probably not take this medication.
   
• Neither of these medications should be used in the cat.
   
• Carprofen does not inhibit matrix production by cartilage cells.

For more information on rimadyl click here, or go directly to the Pfizer animal health rimadyl area at www.rimadyl.com

DERAMAXX (Deracoxib)

As research progresses to make safer arthritis medications for both humans and animals, the coxib class of NSAIDs was developed. Inflammation is in part medicated by biochemicals called “prostaglandins.” While some prostaglandins mediate inflammation, other prostaglandins are needed for normal healthy cell function. The trick is to inhibit the “bad” prostaglandins without interfering with the “good” prostaglandins.

It turns out that an enzyme called Cyclooxgenase-1 (Cox-1) is responsible for making the “good” prostaglandins while Cyclooxgenase-2 (Cox-2) produces the bad ones. Most NSAIDs (aspirin, Ibuprofen, etc.) inhibit both enzymes. Rimadyl and Etogesic primarily inhibit Cox-2, but not until the coxib class was developed was it possible to inhibit Cox-2 without also inhibiting Cox-1 in part.

• Deramaxx is available as a chewable tablet and is for once a day use.
   
• We still recommend blood work every 6 months during the long term use of any medication )including this one).
   
• Of all the oral NSAIDs currently available for dogs, this is probably the most expensive but depending on the results obtained may be well worth it. It is not only the safest NSAID but probably the strongest pain reliever.

For more information about Deramaxx, click here.

CORTICOSTEROIDS

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:

• immune suppression
   
• poor wound healing
   
• poor ability to grow hair
   
• excessive thirst
   
• muscle weakness

Using thise medications to control arthritis pain is not desirable in the long term and one of the other medications mentioned would be a better idea.

SLOW-ACTING DRUGS OF ARTHRITIS

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. Theoretically, after months of using the slow-acting treatments it may be possible to cut back or even discontinue the fast-acting drugs listed above.

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 NSAIDs, 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.

• Because these substances are classified by the FDA as “nutriceuticals” (ie nutrients with medicinal properties) rather than as “drugs,”  the usual rigorous testing for efficacy has not been required. As a result, the optimal dosage has not been determined and almost every product has a different dose recommendation. Some experimentation may be necessary.
   
• These products are not likely to be helpful for spinal arthritis as the joint composition of an intervertebral disc (the joint of the spine) is totally different from those of other bones.
   
• These products can be used in both dogs and cats.
   
• These products often complement treatment with NSAIDs.

ADEQUAN^® INJECTIONS

Adequan^® is an injectable “polysulfated glycosaminoglycan” (mostly chondroitin sulfate), a cartilage component but instead of coming from sea mollusks, adequan is derived from the windpipe cartilage of cattle.  Adequan has numerous beneficial effects for the arthritis patient including the inhibition of harmful enzymes involving joint cartilage destruction, stimulation of cartilage repair, and increasing joint lubrication. These effects go far beyond simply providing plenty of chondroitin sulfates as a “building block” for damaged cartilage.

• Adequan is given as an injection and so is able to reach all joints but it seems to have a special affinity for damaged joints.
   
• Adequan should be avoided in patients with blood clotting abnormalities as a matter of caution. (At excessive doses tested in normal patients, abnormal clotting resulted so it is best not to take a chance in an abnormal patient.)
   
• Adequan is best given as a series of injections, twice a week or so until a response is seen but not exceeding eight injections. After an effect is seen, Adequan injections are given on an “as needed” basis.
   
• Adequan is formally approved for use in dogs and horses but may also be used in cats with good results.
   
• Adequan may be combined with NSAIDs and/or oral slow-acting drugs of arthritis.

OMEGA 3 FATTY ACIDS

Certain fats have been found to have anti-inflammatory properties. While this finding has primarily been utilized in the treatment of itchy skin, many arthritic dogs and cats have also benefited from supplementation.  While there are no toxic issues to be concerned with, these products require at least one month to build up to adequate amounts. Effects are not usually dramatic but can be helpful.

• Omega 3 fatty acids can be used in dogs and cats.
   
• Omega 3 fatty acids can be combined with any of the above treatments.

MSM

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 or industrial grade.  One might wonder why a sulfer source would be helpful in treating arthritis. The glycosan inoglycans 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).

Because it is a nutriceutical and thus not required by the FDA to be subjected to tests of safety or efficacy, its effectiveness is still “up in the air.” There is a tremendous human market for this product thus little motivation for manufacturers to finance expensive testing of this nature.

• MSM can be used in dogs and cats.
   
• MSM can be combined with any of the above products.

ANTI-OXIDANTS AND FREE RADICAL SCAVENGING

Free radicals are harmful biochemicals which 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 and the damage to our brains, skin, joints and to every tissue as the primary cause of aging. Normally, our bodies use natural anti-oxidants to inactivate free radicals and by supplementing 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. 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.

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.