Investigating IRAP

WHAT’S THE HYPE ABOUT?

More and more riders are investing in IRAP® treatment for their horses. But what is this treatment, how does it work, and which horses can benefit? HQ investigates…

NORMAL INJURY PROCESS

When a horse’s joint becomes injured either through physical or chemical means, the body’s normal repair process includes the release of pro-inflammatory chemical mediators that can actually accelerate damage to the cartilage and joint. These mediators include a chemical called interleukin 1 (IL-1), which binds to the IL-1 receptor on the surface of the joint and is responsible for causing ongoing inflammation, pain and lameness.

Osteoarthritis continues to worsen due to the proinflammatory mediators like IL-1.

Structure of Interleukin-1

INTERLEUKIN-1

Interleukin-1 (IL-1) is a pro-inflammatory protein that is found in increased quantities in diseased joints, such as those suffering from osteoarthritis. IL-1 is a potent chemical signal that activates many of the elements of the pathway of inflammation. The release of IL-1 and other proinflammatory chemicals, therefore, leads to inflammation and further disease. In the case of joints, IL-1 production results in cartilage damage and worsening osteoarthritis. As tissue damage increases within the joint, additional IL-1 is produced, perpetuating the cycle of inflammation and resulting in further osteoarthritic change.

WHAT IS IRAP®?

IRAP®, which stands for Interleukin-1 Receptor Antagonist Protein, was originally developed in Europe and has been used extensively in Germany. It is an anti-inflammatory treatment for joint disease in horses that works by counteracting the pro-inflammatory cascade triggered by the protein interleukin-1.

IRAP® works in the horse by blocking IL-1 from binding to its receptor at the site of injury or disease. In this way, it stops the cascade of inflammation triggered by IL-1 and slows the progression of osteoarthritis.

HOW IS IRAP® ADMINISTERED?

A typical treatment with IRAP® begins by drawing approximately 50ml of blood from your horse. This autologous blood (blood from your own horse) is then incubated overnight in a syringe that contains pre-treated glass beads designed to isolate and amplify the horse’s naturally occurring IRAP®. The IRAP® is then concentrated by spinning in a centrifuge and is sterilely prepared into

DEGENERATIVE JOINT DISEASE

Degenerative joint disease (or osteoarthritis) is one of the biggest causes of poor performance and a decreased competitive career length in horses. This is true for all types of equine athletes, whichever discipline they compete in. Both young and old horses can be affected by degenerative joint disease resulting in a loss of athletic ability and the need for possible early retirement.

Degenerative joint disease is usually the result of one of several factors, which can include poor conformation, advancing age, hard work, lack of conditioning, previous trauma, developmental disease and multiple physiological factors. The clinical signs of degenerative joint disease include lameness, poor performance, stiffness, and joint swelling. These signs are the result of synovitis (inflammation of the joint lining) and progressive cartilage damage within the joint.

Articular cartilage typically has a smooth surface and is a critical component of joint stability and fluid motion. It is also resilient and acts to absorb the tremendous amount of force exerted through movement. Damage to cartilage initiates a cycle of inflammation and pain, increased inflammatory protein production and thus further cartilage degeneration causing the clinical signs to worsen. This process can become a vicious cycle if not treated and arrested quickly. Over time, bony changes occur, which show up as abnormalities on radiographs (X-Rays).

Conventional therapies for osteoarthrits (in no particular order) include rest, nonsteroidal anti-inflammatory drugs, intraarticular (joint) injections with hyaluronic acid and corticosteroids, certain intramuscular and IV agents, oral supplementation with products like glucosamine and chondroitin sulphate, and extracorporeal shockwave therapy.

Healthy cartilage (left) versus diseased cartilage (right) in osteoarthritis.

individual dose syringes for injection back into the horse. These syringes are stored in a freezer until they are ready to be used. IRAP® is typically injected into a joint once every 7-10 days for 3-5 treatments in total. The most significant effects tend to be seen after the second and third doses. Rest is usually recommended for at least 5-7 days following injection, as per your vet’s instructions.

NOTE: Joint injections come with a risk of joint infection, which can prove fatal. Therefore, joint injections should only be used as a last resort when other alternatives have been explored.

WHAT IS IRAP® USED FOR?

IRAP® is used for: • Cases with lameness isolated to specific joints that demonstrate mild to moderate radiographic signs of degenerative joint disease. These cases tend to respond the best to treatment with IRAP. • Horses with joint disease who have failed to respond to other more traditional joint therapies like antiinflammatories. • Post-surgical joint therapy in cases with focal cartilage damage or after arthroscopic removal of chips. • Horses with synovitis (inflammation of the joint lining).

IRAP® is not recommended for use in tendon sheaths or bursae, in bone cysts, in horses with advanced osteoarthritis or in joints where there are bone fragments, fractures, meniscal or ligamentous injuries.

WILL IT HELP MY HORSE?

IRAP® has had some very encouraging initial results, suggesting that it improves lameness and decreases joint swelling. However, as with all treatments, it will not be successful in all cases. It is likely that other therapeutics may also be needed in conjunction with IRAP® therapy to treat horses with osteoarthritis.

NOTE: IRAP® cannot reverse any permanent damage that often exists in joints with osteoarthritis but may serve to prevent further inflammation and reduce the progression of the disease.

CAN I COMPETE?

There are currently no restrictions on its use in competition, other than it cannot be administered on the day of the competition. However, competition rules do change, so owners are advised to check with their regulatory body for the most up-to-date information.

NOTE: Horses usually require rest and hand walking for several days after any kind of joint injection, so IRAP® would usually be administered well in advance of a competition.

FINAL THOUGHTS

IRAP®is another therapy to be added to the battery of tools to combat osteoarthritis in the horse. IRAP® is very exciting because of its potential for a long-term impact on osteoarthritis by stopping the inflammatory cascade. The research on IRAP® is ongoing, but the results to date have been very encouraging. For more information and to assess the suitability of the treatment for your horse, chat to your vet.