Tendon lacerations generally result from accidents, such as a horse running into a sharp object or getting a leg caught in a wire fence, writes Les Sellnow in the September edition of The Horse
. The horse can suffer injury to either the tendons in the front of the leg (the extensors) or those on the backside (the flexors).
"Lacerations of the extensor tendons rarely need specific treatment beyond wound care," said Dr. Nathaniel White II, professor of surgery at the Marion duPont Scott Equine Medical Center at Virginia Tech in Leesburg, Va. "The tendon ends are often shredded and cannot be brought back into apposition. They should not be sutured as the tendon will heal adequately without suturing. Even when segments of tendon 30 to 40 centimeters long are lacerated, the tendon will eventually heal with good function.
"The wound should be closed if possible," White continued. "If closure is not possible, the wound should be bandaged and granulation tissue allowed to fill the wound. The horse should be placed in a stall and walked carefully. If knuckling occurs, a thick bandage should be used to prevent injury to the front of the pastern and fetlock. Walking is indicated, and horses learn to use the limb in several days in most cases."
Flexor tendon lacerations, according to White, should be sutured whenever possible. If the wound is clean, primary debridement (removal of the foreign material and contaminated or devitalized tissue) and suturing should be completed immediately. If the laceration is contaminated or infected, stabilization of the limb with a splint or cast is indicated until it can be debrided on each of several days in preparation for suturing.
If the tendon ends cannot be sutured, the wound must be surgically debrided. The wound should be closed if contamination is reduced sufficiently to prevent infection. If contamination is still present, the wound should be left open for drainage even under a cast.
The application of a cast is almost always necessary when dealing with lacerated flexor tendons, White said. A partial cast up to the knee or hock is normally used, but a full limb cast might be required for lacerations of tendons in a hind leg. According to White, the cast should be left on a minimum of four weeks for single tendon lacerations. Six to eight weeks of cast support might be needed before adequate strength is present in the healing tendon.
After cast removal, the leg is supported with a stiff bandage. A splint may be required during the first two to three weeks after cast removal to allow the tendon to gain strength. If the deep flexor tendon is involved, an extended heel shoe should be applied immediately after the cast is taken off. Injured horses should be kept in a stall and walked on a daily basis. Sometimes injured horses can be turned out as early as four months after injury, but six months of stall rest usually is necessary for severe lacerations.
The bad news is that the prognosis for any tendon laceration injury always should be guarded. Somewhere between 50%-60% of horses that suffer this type of injury return to some type of performance, which is often less strenuous than the previous level of work. The good news is that a high percentage of horses can be used for breeding after tendon laceration repairs.