Index

Introduction
Homeostasis
Life Span
Systems
Regulatory Functions
Nervous System
Eyes
Ears
Nose
Tongue
Brain
Endocrine System
Hypothalmus
Pituitary
Thyroid
Adrenal
Nutritional Functions
Excretary Functions
Urinary System
Kidney
Bladder
Colon
Distributive Functions
Cardiovascular System
Blood
Respiratory System
Protective Functions
Reproductive Functions
Musculo-Skeletal System
Cancer
Arthritis
Obesity
Diabetes
Cushing's Disease
Heart Disease
Teeth
Skin and Coat
Conclusion
References


Arm Your Dog Against The Effects Of Aging
Arthritis And Degenerative Joint Disease

Although your older dog may not develop cancer, chances are likely it will experience arthritis in its lifetime. Twenty percent of adult dogs and virtually all old dogs are arthritic.

Environmental, dietary and genetic components make analysis of the arthritic disease process difficult. Here, we are using the term arthritis for the range of degenerative joint diseases found in dogs, including hip dysplasia, osteochondritis, osteoarthritis and spinal conditions. Although hip replacement and other surgeries can improve the dog's quality of life dramatically and extend its useful life significantly, costs of these alternatives generally preclude their application except in the case of working dogs.5-7 Medical treatment rather than surgical treatment has become the norm with newer, nonsteroidal anti-inflammatory and nutraceutical products showing great promise.

We emphasize degenerative joint disease because it is universal among olddogs and because it is a condition that usually can be treated satisfactorily without surgery or heroic measures. The debilitating effects of degenerative joint disease often can be reduced to the point at which the decision routinely is made to continue the life of the dog. We encourage owners to read the following carefully, as it may make the difference between deciding to treat the older dog, letting it suffer or putting it down.

Disease-Modifying Osteoarthritis Substances. Two categories of substances with documented disease-modifying effects are available: disease-modifying osteoarthritis drugs and disease-modifying osteoarthritis nutraceuticals.

Disease-Modifying Osteoarthritis Drugs-This new class of drugs is represented by polysulfated glycosaminoglycan (PSGAG). Under the trade name Adequan®8, PSGAG has received approval from the Food and Drug Administration for injectable use in dogs. Adequan is injected intramuscularly, thus avoiding the risk of introducing a pathogenic organism into the joint, which can occur during intra-articular injection. (It is very difficult to enter an encapsulated joint space without running the risk of subsequent infection in that joint.) A course of treatment is eight shots, normally administered by a veterinarian every few days.

It appears to have a beneficial effect because it not only promotes cartilage growth but also repairs cartilage damage and helps prevent injury by inhibiting those enzymes responsible for the breakdown of the various articular components.9 Specific applications include: hip dysplasia, ruptured cruciate ligaments, osteochondritis dissecans (a specific type of inflammation and distortion of the cartilage), spondylitis (inflammation of the vertebrae), traumatic joint injury and geriatric osteoarthritis. PSGAG rapidly is becoming the "wonder drug" because it quickly produces results and slows the progress of degenerative joint disease. Adequan is not a cure, and it is too expensive to be used as a long-term treatment. Due to its high cost and the fact it must be vet-administered, the real medical problem is what to do after treatment with Adequan.

* Disease-Modifying Osteoarthritis Nutraceuticals-Cosequin® by Nutramax Laboratories Inc.10 is a new disease-modifying nutraceutical containing glucosamine to stimulate cartilage matrix production and chondroitin sulfate to inhibit cartilage degradation. Nutramax discovered the glucosamine-chondroitin synergistic effect on cartilage matrix enhancement and holds the patent for combining glucosamine salts (HCL, sulfate or hydroiodide) with chondroitin sulfate to achieve a disease-modifying level of effectiveness not otherwise reachable by providing the compounds separately in humans, horses and dogs.11-14

For the same reasons we like Adequan (and Rimadyl® and EtoGesic(tm), which we discuss next), we like Cosequin. Published articles, quality manufacturing, ingredient tests and product research back up these products. And, unlike many nutraceuticals that are formulated based on a review of the literature, this research was done on the actual products. Nutramax has done the primary research to back up the formulation of its product, has obtained two U.S. patents15 and has manufactured in accordance with pharmaceutical good manufacturing practices standards. Nutramax leads the way in documenting its nutraceutical product through multiuniversity studies.16

Nonsteroidal Anti-Inflammatory Drugs. These drugs inhibit the synthesis of chemical messengers called prostaglandins, but they are unable to differentiate between those that are protective and those that are inflammatory. As a result, NSAIDs can have both beneficial and adverse properties simultaneously. Inadequate control of hydrochloric acid, loss of buffering ability and deficient protective mucous secretion are just a few of the effects that can lead to gastrointestinal tract problems. Geriatric patients are more at risk for kidney problems because they are more apt to need prostaglandins to maintain renal blood flow and urine output. The new NSAIDs are more effective and safer because they place less stress on the kidney, liver and gastrointestinal tract.

* Carprofen-This drug marketed by Pfizer under the trade name Rimadyl17 literally has restored thousands of dogs to full function, but as more data come in, side effects are beginning to manifest that did not appear in the original testing. Some dogs have died, and other side effects of carprofen have been reported such as vomiting and anorexia.18 It should be noted, however, that the available list of side effects is similar for most NSAIDs. Pfizer recommends that "Since a significant number of patients receiving Rimadyl are older dogs, it is advisable to conduct a geriatric examination and to consider appropriate laboratory tests to establish hematological and serum biochemical baseline data prior to administration of any NSAID. Periodic monitoring may be appropriate in certain patients."19 At the time of this writing, 122 dogs out of the many thousands treated have died.20 For the vast majority of animals treated, carprofen is both safe and effective. If a dog is tolerating it well and the intended benefits are being realized, there is no reason to discontinue its use. There is onecaveat specific to carprofen: Labrador Retrievers may be more sensitive to it than other breeds. All NSAIDs, however, have safety concerns.

* Etodolac-A newer, potentially safer and more effective NSAID is marketed under the trade name EtoGesic.21 Etodolac has been used for a number of years in humans. Recently it has been FDA-approved as the first once-a-day, non-narcotic, nonsteroidal anti-inflammatory, indole acetic acid class drug with both anti-inflammatory and analgesic properties for treatment of canine arthritis. This stands out for several reasons:

  1. It received approval from the stringent FDA. Good science and rigorous testing are required to obtain such approval, and these tests included six-month, one-year and compassionate use studies of longer than three years. (Compassionate use studies run longer than the FDA-required time period and are used to obtain the benefits over a longer duration. These are opposed to LD-50 studies, for example, which generally are short-term and show the dosage required to kill 50 percent of the test subjects.) Some practitioners use the many drugs not approved for dogs by the FDA based on anecdotal evidence attesting to their efficacy. Now there is an FDA-approved option.
  2. The once-a-day dosage regimen creates convenience and a higher probability of owner compliance. Despite good intentions, few owners-especially if they are employed, have families and have other pets-will adhere to a two-, three- or four-times-per-day dosing schedule for very long, i.e., for the rest of the dog's life. This especially is true if the NSAID must be given after feeding. EtoGesic can be given with or without food.
  3. Force plate studies have been done for EtoGesic. The force plate lets the researchers know the amount of weight the dog is putting on any given limb, and it is the best nonsubjective evaluation available. A multiuniversity study revealed that after treatment with EtoGesic, dysplastic dogs could tolerate five times the downward force exerted throughout their stride and four times the maximum weight they had been able to bear on the most affected rear leg. Our review of the literature and the FDA-filed New Animal Drug Application, and our discussions with both veterinary clinicians and researchers lead us to conclude that EtoGesic is becoming the NSAID of choice for degenerative joint disease.

Nutraceuticals. Nutraceuticals are an emerging category somewhere betweendrugs and foods. They are unregulated by the FDA; this usually means one knows very little about what one gets unless the company has done extensive research to support the safety and efficacy of its product (such as the previously described Cosequin). The definition of nutraceutical has become all-encompassing. Nutraceuticals used to treat arthritis fall into two general categories: cartilage-supportive substances and anti-oxidant free-radical scavengers.

* Cartilage-Supportive Substances-Many substances have been theorized to help cartilage form, grow, regenerate and repair, and some have shown promise in animals. It is important to understand that besides the studied DMODs' compounds listed earlier, other compounds-such as glucosamine alone (Prosamine® by Virbac) or perna mussel (Glycoflex® by Vetri-Science)-have been suggested for treatment of degenerative joint disease in dogs although no U.S. veterinary-controlled trials exist. Dog owners should beware that there are many copycat and knockoff nutraceutical products containing glucosamines with or without chondroitin sulfate. These are supported with wonderful tabloid testimonials and undocumented claims rather than studies published in peer-reviewed journals.

Few of these products have consistent bioavailability (the extent to which a drug or other substance becomes available to the target tissue after administration). Standardization is so difficult it is doubtful that many nutraceuticals and herbals even are what they purport to be. Few are manufactured to strict standards.

* Anti-Oxidants-Anti-oxidant therapy has been touted to cure just about any ill imaginable, and many products are available. Although we somewhat are convinced anecdotally that anti-oxidant therapy does work in some disease processes, tabloid medicine has embraced anti-oxidants with enthusiasm and has exaggerated the claims to the point at which they are no less than spectacular.

Anti-oxidants "scavenge" free radicals-those unstable, highly reactive molecules containing an atom with an unpaired electron-that cause damage to cartilage and other tissue. Studies have shown the hydroxyl, superoxide and peroxide free radicals are harmful to cells.

Free radicals play a major role in oxidative damage (otherwise known as the aging process); however, little work has been done to support the contentions that oral anti-oxidants are effective against prevention of osteoarthritis in living canines.22 Anti-oxidants do have an anti-inflammatory function and can lessen the pain associated with this condition. Again, nutraceuticals are not regulated by the FDA; we recommend only those anti-oxidants manufactured to human food grade good manufacturing practices standards, and we have a preference for products meeting these minimum standards, such as Pycno- genol®,23 which contains proanthocyanidins from pine bark or Proanthozone®,24 which contains grape seed extract/meal bioflavonoid.25-26 (Bioflavonoids are a group of low molecular weight plant substances with recognized anti-oxidant properties and the ability to inhibit the activity of certain enzymes that cause inflammation in the body.)

Multipharmacy Anti-Arthritis Therapy. Arthritis is a complex disease with an etiology that involves genetic, stress and nutritional factors. Many older dogs have been restored to pain-free function with an initial regimen of Adequan, maintenance treatment with Rimadyl or EtoGesic and concurrent nutritional support with Cosequin. The Adequan-EtoGesic-Cosequin treatment sequence is being used by many practicing veterinarians.27 Current studies strongly suggest Cosequin use may reduce the amount of maintenance NSAIDs required to achieve a level of functional comfort.28 Anti-oxidants such as Pycnogenol and Proanthozone and cartilage-supportive products such as Prosamine and Glycoflex may be with the documented compounds in the future, although to date, little definitive research exists on these ancillary compounds in multipharmacy therapy.

Even while your pet still has plenty of spring in its step, provide proper care with a good exercise regimen and healthy diet. Some old-age conditions are linked to a dog's diet.

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