Boosting Equine Joints’ Wear And Repair Cycle

Ryan Curtis goes over the possible equine joint damage as well as how repair to those joints can take place.

When the natural “wear and repair” process in a horse’s joints is disrupted, non-infectious degenerative joint disease (DJD) begins. This disease is a vicious cycle of destructive enzymes attacking the fluid and cartilage.

Continued disruption to the joint fluid can lead to irreversible cartilage fragmentation, and eventually the complete destruction of the cartilage. DJD is estimated to cause one-third of all lameness cases.

Balanced Joint

A healthy equine joint is a complex system of internal and external tissues that provide stability and protect the joint while allowing for freedom of movement. During routine activity, a functioning balanced joint is in a constant state of wear and repair.

As normal forces are exerted on the joint, cells are actively regenerating and repairing the components of damaged cartilage while replacing the synovial fluid in the joint. This constant renewal, repair and replacement cycle assures that no cartilage loss occurs and a functionally balanced, healthy joint environment is maintained.

The synovial membrane is the inner layer that acts as a permeable barrier and is very important to the joint’s balanced “wear and repair” cycle. This membrane filters blood, excludes the protein and adds hyaluronic acid (HA) to form synovial fluid. This fluid acts as the boundary lubricant of the joint capsule and synovial membrane, to keep unwanted cells out of the joint cavity. It also removes waste and nourishes the cartilage.

The cartilage cells repair and replace components under normal wear and tear. The tough fibers and water-rich matrix give it “coil spring” resistance to shock and shear forces, and the capability to distribute loads evenly into the subchondral bone.


When the wear and tear of daily use, a misstep, incorrect shoeing or abnormal forces cause trauma, the natural “wear and repair” cycle within the joint is disrupted. The joint then is susceptible to equine non-infectious DJD, often called osteoarthritis. Osteoarthritis most commonly affects the hocks and coffin joints with the most severe effects on the high-motion knee and fetlock joints.
Symptoms of DJD include:

• Swelling
• Wide stance
• Stiffness or changes in gait
• Reduced range of motion or shortened stride
• Reluctance to perform


Detecting and treating joint dysfunction before cartilage and/or bone damage occurs can prolong the working life of the performance or pleasure horse. Treating with tried and proven products produces consistent results. Using medications with FDA approval assures that a product is:

• proven safe and effective in controlled studies

• manufactured following FDA purity and potency guidelines.

The following are FDA-approved treatments and how they work:

Non-steroidal anti-inflammatory drugs (NSAIDs) act rapidly and are easily administered for the short term relief of pain and inflammation. Potential side effects are blood disorders, gastrointestinal ulcers and renal damage.

Corticosteroids are powerful anti-inflammatory drugs that minimize pain and rapidly decrease the inflammation of soft tissue. They can be valuable when used judiciously.

Corticosteroids interrupt not only the inflammatory process, but the repair process as well.

Sodium hyaluronate helps restore the function of the hyaluronic acid within the joint to improve the lubrication, stimulate natural production of HA and generally improve the synovial fluid.

Polysulfated glycosaminoglycan is a naturally occurring complex molecule that is the essential building block of the cartilage matrix. Marketed only as Adequan (polysulfated glycosaminoglycan), this product travels into injured joints and stimulates production of new cartilage while relieving the symptoms of noninfectious degenerative joint disease. Adequan is the complete treatment for noninfectious degenerative joint disease.

Reverse Joint Damage

Proven to relieve the symptoms of osteoarthritis, Adequan breaks the destructive disease cycle, inhibits cartilage damage and stimulates the cartilage repair process. Extensive studies of Adequan have shown that it readily passes through the synovial membrane and is taken up into cartilage by diffusion. This results in the concentration and progressive accumulation of Adequan at the site of injury.1

“This is the only FDA-approved disease modifying osteoarthritic drug available for equine joints. It has been scientifically proven and more than 80 equine trials have been published around the world,” says Victoria Maxwell, DVM, technical services veterinarian for Luitpold Pharmaceuticals. Clinical studies show that one intramuscular injection of 500 mg Adequan i.m. induces a rapid, significant increase of synovial hyaluronic acid within 24 hours. Studies show that two hours after the first Adequan i.m. injection, therapeutic levels are detected in cartilage and subchondral bone in the joint and persist for up to 96 hours.2

Thus the treatment regimen of one dose every four days for seven treatments.

“The parameters veterinarians, trainers and horse owners are looking for in joint therapy include stride length, knee flexion and lameness score,” says Gary White, DVM, of Sallisaw Equine Clinic in Sallisaw, Okla. He conducted a randomized, blinded positive-controlled study with Adequan intramuscular injections given every four days for seven treatments. The Adequan i.m.-treated horses showed the following results:

• Stride length, 98 percent improvement
• Knee flexion, 95 percent improvement
• Lameness score, 88 percent improvement

Early recognition and treatment of DJD can limit the damage and restore the normal “wear and repair” balance in the joints before permanent cartilage or bone damage occurs. 



2. July 2007 randomized, blinded positive controlled study conducted by Gary W. White, DVM, showed Intramuscular Adequan® i.m. (POLYSULFATED GLYCOSAMINOGLYCAN) to be significantly more effective than intravenous Polyglycan for relief of lameness, stirde length, carpal flexion and in reducing carpal swelling. Study was conducted over a 33-day period in two groups of eight horses each. Group A received 500 mg/5 mL intramuscular Adequan® i.m. and Group B intravenously received 5 mL Polyglycan IV. The Complete Freund’s Adjuvant (DFA) carpitis module model was induced in all horses. All treatments were administered twice weekly beginning on Day 5 after model induction for a total of 7 injections, as this is the approved regimen for Adequan® i.m., and no dosing information is available for Polyglycan®. Polyglycan is a registered trademark of ArthroDynamic Technologies, inc.

Ryan Curtis is an account manager for The Duff Co. of Kansas, Mo.

This article was underwritten by The Duff Co. of Kansas City, Mo., on behalf of Luitpold Animal Health of Shirley, N.Y.


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