Osteoarthritis (OA) is a commonly encountered cause of lameness and poor performance in the horse. It is a disease process of joints characterised by cartilage degeneration, subchondral bone sclerosis, osteophyte formation, varying degrees of synovial inflammation and periarticular tissue fibrosis.

OA is most frequently manifested clinically as a slowly progressive lameness which can often be bilateral. There may be joint pain, a decreased range of motion, variable joint effusion and inflammation but no systemic effects. It is important to remember that OA can be present in a joint with little or no radiographic evidence of bony changes if the radiographs are taken in the early stages.

OA can occur at any age. Generally, it is seen in older horses but can also be commonly seen in high-performance horses. One or multiple joints may be affected.

The main cause of OA is trauma. Often this causes stems from overuse or conformational inadequacies that predispose an athletic horse to inappropriate biomechanical forces on cartilage. Most often, the inflammatory process begins in the synovium, cartilage, joint capsule or subchondral bone and quickly initiates a cascade of inflammatory mediators from the primary tissue of insult.

There are many products on the market for managing OA, either injectable or oral formulations. The clinic stocks two injectable arthritis supplements, Arthropen Vet and Matrix 6000. The active ingredient in Arthropen Vet is pentosan polysulfate which has been shown to have anti-inflammatory properties and stimulates hyaluronic acid synthesis. This can be given either into the muscle or into the joint, the latter method needing to be done, in a sterile manner, by a vet. The advantage of systemic treatment is it can treat more than one joint at a time. A course of Arthropen Vet is a series of 4 intramuscular injections one week apart and then a top-up dose once a month.

The active ingredient in Matrix 6000 is sodium hyaluronate. Hyaluronic acid is an essential component of articular cartilage and synovial fluid.

In performance horses, Matrix 6000 may be administered prior to competition as an aid in reducing joint inflammation and restoring joint function. The injection needs to be given intravenously and can be given up to three times, one week apart if needed.

4cyte Equine is an oral arthritis supplement for horses. This product contains Epiitalis, a plant oil extract patented for its ability to proliferate chondrocyte cells (the main cells in cartilage) which actively ‘tips the balance’ back in favour of the production of healthy cartilage instead of degeneration. It needs to be given daily.

Synequin is another oral arthritis supplement to be given daily which contains a unique combination of:

• Chondroitin sulphate – a key nutrient for healthy cartilage and joint fluid.
• Glucosamine hydrochloride – one of the basic building blocks for cartilage and joint fluid.
• N-acetyl D-glucosamine – facilitates the action of glucosamine.
• Zinc – important in the metabolism of cartilage and bone.
• Vitamin C – a water soluble antioxidant vitamin.

If you suspect your horse is suffering from OA, please get in touch with one of our vets for further advice.