Regenerative Treatment Options for the Lame Horse

Michael Caruso III, VMD, DACVS-LA, Surgeon/Sports Medicine Clinician, Tennessee Equine Hospital
Last month we discussed different techniques used to diagnose lameness in the horse. This month, we introduce regenerative treatment options your veterinarian may recommend to help treat the source of pain causing lameness. These options may include interleukin-1 receptor antagonist protein (IRAP), platelet-rich plasma (PRP), mesenchymal stem cells, and a combination of PRP and IRAP (Pro-Stride).

IRAP is also called autologous conditioned serum. This treatment is produced by drawing blood from the horse in a sterile manor, incubating the blood in special syringes with glass beads, conditioning blood components, primarily monocytes (cells), to increase production of a protein that helps to block a pro-inflammatory cytokine interleukin-1.  Interleukin-1 is a pro-inflammatory substance produced in the process of degenerative joint disease or osteoarthritis. IRAP treatment is one option veterinarians have to help slow the process of arthritis and cartilage degeneration. The IRAP treatment is injected directly into the joint or joints your veterinarian suspects are developing arthritis with the intent of preventing more cartilage destruction and slowing the degeneration of the joint.

Platelet-rich plasma (PRP) is another blood-derived regenerative product. Blood is obtained aseptically from the horse and centrifuged, or spun-down, in special containers.  The preparation process concentrates platelets, circulating in the bloodstream, into a small sample that can easily be injected into a joint or into a tear in a tendon or ligament. Platelets are a vital source of growth factors, chemokines, and cytokines, all of which are released during the reparative processes occurring in the early phases of tissue healing. PRP also stimulates the delivery of other important pro-healing elements to the site of injury that hasten the repair process. Multiple studies have demonstrated that growth factors released from PRP enhance the healing of soft tissues and promote bone and cartilage regeneration processes. PRP is mainly used to help repair tendon and ligament injuries; however, it also has uses in osteoarthritis and degenerative joint disease in the horse. The concentrate of platelets is injected into a joint or injected into a tendon or ligament tear using ultrasound-guidance.

Mesenchymal stem cells promote tissue regeneration, regulate the body’s inflammatory response from trauma, and can reduce scar formation during the tissue repair process. Following sedation and a local anesthetic, a special biopsy needle is used to obtain bone marrow from the sternum or hip of the horse. The bone marrow is collected in a syringe, packaged, and shipped to a laboratory. At the laboratory, the stem cells are isolated from the bone marrow sample and amplified in special cell culture media. The expansion/amplification process typically takes 2-4 weeks. When enough cells are expanded, your veterinarian is shipped a pre-requested amount of cells that are aseptically packaged into syringes. Typical injections of stem cells contain 20-40 million cells and the injections volumes are usually only several milliliters.

Stem cells are used to help regenerate joint cartilage, rebuild tendon and ligament fibers, and help heal chronic wounds.
A newer product that has been evaluated scientifically combines PRP and IRAP. The company name for the product is Pro-Stride. This regenerative product also involves obtaining a blood sample from the horse and placing the sample in special containers that are centrifuged to isolate the desired portions of the blood. As discussed in the IRAP and PRP sections, this product combines the benefits of the anti-inflammatory and pro-healing aspects of IRAP and PRP respectively into one injection. This product has been evaluated in models of arthritis in the horse and has become widely used and accepted as a new treatment option for horses with degenerative joint disease.

A common theme of these treatments is harnessing the pro-healing and anti-inflammatory produces normally circulating within the body and concentrating these important substances in a small volume that can be injected into the specific area that is causing pain and lameness in the horse. Many issues veterinarians face with tendon/ligament healing or arthritis revolve around the body’s inability to concentrate pro-healing substances in one location quickly. With these regenerative products, veterinarians are able to deliver very concentrated amounts of cells to the exact location that is causing pain and lameness. Using these techniques, veterinarians are able to accelerate the healing time and improve the quality of healing. Please contact your veterinarian or Tennessee Equine Hospital for questions regarding regenerative therapies and their application for your horse.

Editor’s Note: More resources for information about regenerative medicine include the Virginia-Maryland College of Veterinary Medicine at: and UT College of Veterinary Medicine: 

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