With so many options for joint supplements on the market today, how does anyone know which ones actually work? Or remember how to use each one? This article’s purpose is to do just that. Here we have laid out the important details of today’s available injectable joint supplements so that you and your veterinarian can make an educated decision for your equine athlete.

Hyaluronic Acid (HA) – Legend, Polyglycan

Injecting HA is a common and well-known practice to maintain healthy joints in performance horses. HA is a large molecule that is a normal component of synovial fluid, as well as the lining of articular cartilage, providing both cushion and lubrication to your horse’s joints. Administering HA is thought to do two things: first, it has anti-inflammatory effects that last about two to seven days and second and it restores viscosity, or lubrication, to the joint’s synovial fluid. HA has been manufactured in several forms that can be administered intra-articular (IA) by your veterinarian, IV, IM, or orally. The two most popular forms of IV/IM injectable HA are

Legend and Polyglycan. Legend is an FDA approved product comprised of strictly hyaluronic acid and is given IV at a dose of 4 mL (40mg) once per month. Legend is specifically labeled to be used for non infectious synovitis (joint swelling) of the carpus (knee) and fetlocks (ankle). To prove that the product reaches the joint, the company conducted research by placing a radioactive marker on the molecules, injecting it IV and then searching synovial fluid for the marker. However, the concentration of active ingredient that reaches the joint post-IV/IM injection is controversial. Polyglycan is composed of HA, glucosamine, and chondroitin sulfate, and is made to be a post-surgical lavage of arthroscopic procedures. It is commonly given IV or IM at a dose of 10mL (50mg HA/1000mg glucosamine/1000mg chondroitin sulfate) every two to four weeks but this route of administration is not recommended by the company that manufactures Polyglycan.

Acetyl D-Glucosamine

Acetyl D-Glucosamine is a component of HA and an anti-inflammatory agent. Administration of glucosamine provides an essential building block for the body to manufacture its own natural HA. It is commonly compounded to a desired strength and administered IV or IM at an effective dose of 2000mg every two to four weeks.

Polysulfates- Adequan, Pentosan

Currently, there are two popular polysulfates on the market: Adequan and Pentosan. Both Adequan and Pentosan act as anti-inflammatory agents, stimulate natural HA production and synovial fluid production. Adequan is a polysulfate glycosaminoglycan (PSGAG) that works by inhibiting enzymes which break down the healthy components of cartilage and synovial fluid. Therefore, it effectively reverses the process of degenerative joint disease and has been claimed to be a “disease-modifying osteoarthritis drug”. Adequan is FDA approved and can be administered IA, IM, or IV. It is labeled for treatment of osteoarthritis in the carpus and tarsus (hocks). When used as a preventative, Adequan is administered at 5mL (or 500mg) IM every four days for seven treatments and then once every two to four weeks. Research proves that two hours after administration Adequan is at therapeutic levels within the joint. Pentosan is sodium pentosan polysulfate, a hemicellulose extract of plant origin (Beechwood). The compound’s unique fibrinolytic quality gives it the capability to break up scar tissue within the joint, while also increasing blood flow to the joint by breaking up cholesterol within the blood vessels. Pentosan is administered IM at a dose of 6mL (or 3mg/kg) every five to seven days for four injections, then every two to four weeks. The clinical trials are proving Pentosan to be very effective, making this a promising new option to help battle arthritis in performance horses.

Feed Supplements

Many of these joint supplements and others are available as oral feed supplements. These supplements have undergone extensive research in the human and canine fields, but there is a lack in the equine industry. This is due to the fact that human and canine gastrointestinal tracts are capable of absorbing large molecules like glucosamine. The equine gastrointestinal tract is unable to absorb such large molecules and a significant amount of the supplements (investment) are never absorbed. Further research is needed regarding the oral administration to determine the horse’s ability to absorb the product, process its components once inside the body, and then utilize their therapeutic properties in the desired locations.

Overall, when choosing to spend money on products that claim to do something, ASK FOR PROOF. See if the company has research proving what they claim and be sure to read between the lines and analyze every allegation. And, as always, consult with your veterinarian to formulate the best plan for your horse.

Dr. Roth grew up in North Carolina working with Quarter Horses. She earned a bachelor’s degree from North Carolina State University and DVM from Oklahoma State University. Dr. Roth is finishing up an internship with Hassinger Equine Service and will stay on as an associate veterinarian. Questions, comments or suggestions can be e-mailed to Alison.roth@okstate.edu or writing to InStride Edition.