Newer regenerative treatment for equine arthritis is providing positive results

Farm Forum

Degenerative joint disease is one of the biggest causes of poor performance and a decreased competitive lifespan in the horse. This is true for all types of equine athletes, from racehorses through to dressage and show horses. Both young and old horses can be affected by degenerative joint disease resulting in a loss of athletic ability and possible early retirement.

Joint disease/ osteoarthritis is characterized by inflammation within a joint that sparks an inflammatory cascade resulting in the production of a large amount of inflammatory enzymes. Often the process of joint disease is characterized by an inflammation of the synovium (lining of the joint capsule) followed by the progressive destruction of articular cartilage. The development of joint disease can often progress un-noticed because the onset of lameness can be insidious. Often, it is not until an obvious lameness develops that the presence of degenerative joint disease is noticed.

IRAP (Interleukin-1 Receptor Antagonist Protein) is a new and effective intra-articular treatment for joint disease. The IRAP system has been designed to stimulate the horses’ own white blood cells to produce anti-inflammatory mediators and enzymes that can reduce the inflammation present as a result of degenerative joint disease. Initially blood is collected from the jugular vein and incubated for 24 hours in special syringes that contain glass beads that induce the white blood cells present in the blood to produce and secrete therapeutic proteins. After 24 hours the blood is centrifuged and the serum is separated from the red blood cells. The protein rich serum is then split into 3ml doses and the separate doses are frozen for use at a later date. Typically each collection produces enough serum for between 6-8 injections. It is important to note that the injections are only suitable to treat the horse from which the original blood was collected. The injections can be stored for up to 12 months from the date of collection.

When injected into a joint, the protein rich serum stimulates a regenerative response from cartilage cells, through a process of cell division and increased cell recruitment. This is actually what sets IRAP apart from other intra-articular treatments for joint disease. The fact that IRAP stimulates cartilage cells means that it has a disease modifying component as well as an anti-inflammatory component. The serum also contains cytokines that act to reduce inflammation within the joint. In addition there are other anti-inflammatory proteins produced during the incubation process that work synergistically with the cytokines to further reduce the inflammation within the diseased joint.

What does the treatment involve?

The therapy involves three joint injections at 7 day intervals. Most positive effects are seen after the second and the third treatment and the majority of horses will be sound after the third injection. Once the horse is sound, the horse can resume normal work. If lameness returns after a period of time, any remaining frozen samples can be defrosted and the injections repeated. Often a single injection will suffice at this point and it is unusual for most horses to need to repeat the full course of three injections. However, individual cases can vary and each case will need to be reassessed by your veterinarian if lameness returns.

What cases warrant the use of IRAP?

The cases that generally respond the best to IRAP therapy are those with mild to moderate radiographic signs of degenerative joint disease. Joints where there are fragments of bone (chips) visible on radiographs are not suitable candidates for this therapy. However, IRAP is very useful after arthroscopic removal of any chip fragments. In these cases the anti-inflammatory cytokines and proteins reduce inflammation within the joint and encourage a regeneration response from the damaged cartilage. In post surgical cases, we recommend administering the first IRAP treatment around 10 days after surgery.

Why use IRAP?

IRAP is different from other products because it treats the cause of joint disease and it’s action is aimed at restoring joint lining and cartilage function. Studies performed in Colorado State University show that treated horses demonstrate reduced lameness, improved joint histology (cellular make up) and a tendency towards cartilage preservation.

Dr. Darin Peterson, DVM, was born and raised on a horse and cattle ranch in Rosholt, S.D., and received his B.S. in Animal Science from SDSU. He concentrates most of his work time with large animals. He can be reached at 701-347-5496 or