Clean Run Magazine - May 2007 - 63

would expect an increased incidence of osteoarthritis in our performance dogs due to the increased impact and wear on their joints. Unfortunately, therapy for joint disease has found limited success once the cartilage changes associated with degeneration have developed. >Traditional and Alternative Forms of Treatment Traditional therapies such as steroids and nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the treatment of OA. Unfortunately, many of these drugs may produce undesirable side effects with long-term use, including gastrointestinal, liver, and kidney damage. There is increased interest among our performance dog owners for alternative modes of therapy for the medical management of OA with research focusing on slowing the process of cartilage breakdown and promoting cartilage turnover. This research has led to the development of a new class of products termed “slow-acting, disease-modifying osteoarthritis agents” (SADMOA agents). These products can be further divided into injectable products such as the polysulfated glycosaminoglycan (PSGAG) Adequan® (Luitpold Pharmaceuticals, Shirley, New York); hyaluronic acid, Legend ® (Bayer Corporation, Shawnee, Kansas); and orally administered products such as glucosamine hydrochloride and chondroitin sulfate (Cosequin ® /Dasuquin™, Nutramax Laboratories, Edgewood, Maryland). SADMOA agents are often individual components of healthy cartilage and joint fluid. Studies on how these products actually work are inconclusive but generally include one or more of the following: enhancement of cartilage matrix synthesis, inhibition of enzymes that degrade cartilage, and reduction of joint pain and joint inflammation. Chondroitin sulfate and glucosamine alone (and more effectively together) have been shown to have a biological effect on cartilage. There is a growing body of literature on glucosamine and chondroitin sulfate symptomatic efficacy in clinical trials and in animal models. The use of joint health supplements, such as Cosequin or Dasuquin, is recommended for performance dogs in general due to the stress they place on their joints during competition and training. Repeated stress on the joints can cause excessive wear and tear on the joint cartilage or can lead to ligament or tendon injuries, further destabilizing the joint. Both can then progress to OA. When a performance dog has DJD or OA, the protective cartilage on the surface of the joint gets worn away, and the resultant bone-to-bone contact creates pain. Glucosamine and chondroitin give the cartilage-forming cells (chondrocytes), the building blocks they need to turnover cartilage and to repair the existing damaged cartilage. These nutraceuticals are not painkillers; they actually work by healing the damage that has been done to the existing cartilage. These products generally take at least four to six weeks at a higher loading dose to begin to heal the cartilage and most dogs will need to be maintained on these products the rest of their lives to prevent further cartilage breakdown. Administering joint health supplements to all performance dogs, not just to those who already have OA, provides protection and helps slow down damage to the joint cartilage. Several studies have shown that giving Cosequin prior to joint trauma protected the joints and lessened the severity of cartilage damage. Supplements should be started when dogs begin training and should be continued long-term. Other supplements known as omega-3 fatty acid products such as Welactin®, can also be considered to provide additional benefits to performance dogs. Certain omega-3 fatty acids support joint function as well as overall wellness. Images of a normal joint made up of articular cartilage, subchondral bone (bone beneath the cartilage), joint capsule (surrounding joint tissue which has a significant amount of blood supply and nerve endings), and synovial fluid (joint fluid). Injury or excessive trauma to a joint results in joint inflammation (synovitis). This allows white blood cells to invade the joint. These cells then release destructive enzymes, free radicals, cytokines, and prostaglandins, which cause further inflammation within the joint and a breakdown in the viscosity of the joint fluid. As the negative cascade of osteoarthritis continues the degradative enzymes released by the white blood cells continue to cause further joint inflammation, decrease in viscosity, and begin to cause destruction to the articular cartilage. This pathologic process is noted clinically in the dog by signs of lameness, joint pain, and joint inflammation (swelling and heat). Illustrations courtesy of Bayer HealthCare Animal Health Division, Shawnee Mission, Kansas. May 07 | Clean Run 63

Clean Run Magazine - May 2007

Table of Contents for the Digital Edition of Clean Run Magazine - May 2007