Patty Doyle, D.V.M., M.S., Diplomate ACVS

Typical soft tissue injuries that plague horses range from small to very large lacerations to bowed tendons and torn ligaments. Due to the motion of the lower limb, limited blood supply to some of the tissue, along with other limiting factors, healing may not occur or will require a very prolonged recovery period. Severe lacerations on the front of the cannon bone may require 4-6 months to heal. Bowed tendons or torn ligaments require 6-12 months.

Lacerations are typically treated with surgical closure if possible or are left to heal via second intention (healing from the inside out). In addition, they are also treated with topical antibiotics, systemic antibiotics, bandaging and products to prevent “proud flesh”.

Tendon and ligament injuries are typically treated with cold-water therapy, bandaging, shockwave therapy and prolonged rest with a controlled exercise protocol.

One of the newer modalities of stimulating healing in these types of injuries is the use of platelet rich fibrin. Introduced to veterinarians from human medicine, the technique is used for treating diabetic patient’s lower limb wounds that fail to heal. The patient’s own blood is used to collect platelets that when applied to the area in question, provide a concentration of growth factors for wound healing.

In the horse, the blood is collected into a sterile tube; the platelets and serum are separated from the blood cells and placed into a second tube for activation of the platelets. Upon activation, the liquid turns into a gel that can either be placed onto the bed of a wound or injected into a tendon or ligament lesion.

The healing progression is monitored with periodic bandage changes or ultrasonographic evaluation for tendon and ligament injuries. As healing progresses, the wound will fill in with granulation tissue; and the wound edges will contract making the wound size smaller. Ligament and tendon tears will have the granulation tissue fill in the gap of the torn collagen fibers and eventually with a controlled exercise program will realign as collagen fibers that must then gain strength.

The technique is typically performed on an outpatient basis once it is determined it is a valid treatment for the injury seen. Once placed onto a wound, the bandage is not changed for several days to prevent disrupting the regenerating new cells.  For ligament and tendon injuries, the area is examined with the ultrasound every 6 weeks to ensure healing is progressing as expected.

Tendon and ligament injuries still require prolonged healing time to ensure the new fibers are strong enough to prevent reinjury. However, small tears heal within a few months rather than several months and larger ones that never healed previously are stimulated to heal.

Sites where we have used the technique to date are suspensory ligament lesions, bowed tendons, skin wounds, and corneal ulcers. It is always used in conjunction with many of the same techniques mentioned above such as antibiotics for wounds, bandaging, and controlled exercise.