Download Degenerative joint disease is the number one cause of chronic pain

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 AntiInflammatory Drugs and Cortisone-type Drugs) and Slow-Acting Drugs.
SLOW-ACTING MEDICATIONS
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.
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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.
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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.
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These products can be used in both dogs and cats.
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These products often complement treatment with anti-inflammatory medications.
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 antiinflammatory 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
Certain dietary fats, typically cold water fish oils, 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.
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
MSM stands for “methyl sulfonyl methane” and represents another “nutriceutical” antiinflammatory 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, SAM-e, Superoxide
Dismutase (S.O.D.) and others. Oxtrin® and Comfort Tabs® (S.O.D.) are marketed for joint
support. Denosyl (SAM-e) 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 antioxidants benefit all tissues, including joints.
FAST-ACTING DRUGS
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:
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Carprofen (Rimadyl®, Vetprofen®)
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Deracoxib (Deramaxx®)
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Etodolac (Etogesic®)
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Meloxicam (Metacam®)
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Tepoxalin (Zubrin®)
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Firocoxib (Previcox®)
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.
If a pet has or comes to develop a condition that is not compatible with
NSAID use, one of the analgesics listed below would be a fair alternative.
It is important to mention that cats are uniquely sensitive to all NSAIDs and
it is very tricky to find one that is appropriate. Of the list presented here,
only meloxicam is appropriate for long term feline use and only with some
dose modification.
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:
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immune suppression
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poor wound healing
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poor ability to grow hair
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excessive thirst
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muscle weakness
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predisposition towards the development of diabetes mellitus.
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.
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Tramadol, a narcotic pain reliever similar in many ways to codeine. The pill size makes
it a bit tricky for feline use.
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Amantadine, an antiviral medication found to relieve chronic pain.
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Gabapentin, originally an anti-seizure drug found to have effects on chronic pain especially pain
from pinched or inflamed nerves.
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.
ADEQUAN INJECTIONS
This treatment does not fit readily into the classification system proposed above. 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 sulfate as a “building block” for damaged cartilage.
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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.
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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.)
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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.
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Adequan is formally approved for use in dogs and horses but may also be used in cats with good
results.
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Adequan may be combined with any of the other medications listed on this page.
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