Healing Muscle Injuries Takes Some Time

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Muscle lacerations are generally deep and can understandably worry a horseowner that his horse will never return to work. However, unless a muscle is cut all the way through or has obvious nerve damage, the prognosis for the horse returning to full use is better than with tendon/ligament damage or joint disease.

Even gaping, unsutured wounds with extensive muscle damage heal well with time and proper care. However, returning the horse to his previous work level involves more than healing the cosmetic, outside injury. It may also involve some ingenuity.

Muscle tears always heal with scar tissue, even when they’ve been sutured back together, and the scarred area is not functional. A scar within a muscle is a stiff bit of tissue that lacks the characteristics of a normal muscle. Scar tissue can’t contract or relax, lengthen, shorten or stretch.

Periods of swelling and discomfort are expected when exercise resumes, as the scar tissue undergoes minor breakdowns and remodeling to suit the stresses being applied to it. However, as long as some of the original muscle remains intact, eventually the horse learns to move the area normally and usually return to work.

For the first two to four weeks following a muscle laceration, it’s important to restrict motion in that area, so that a bridge of connective tissue/scar can form between cut edges of the muscle. Too much movement during this healing time will lead to repeated breakdowns of the still weak tissue, resulting in more scarring.

Incomplete healing is indicated when there’s heat and swelling at the injury site (assuming any infection is cleared up) and the horse is in pain when he moves. Once the horse can move around normally at a walk, it’s time to begin a rehab-exercise program, starting slowly.

• Horses with injuries that cut into a muscle need two to four weeks after any infection clears for the initial scarring to become strong enough to hold up to exercise. Stall confinement during this time is advisable.

• Hand walk the horse once he can move comfortably.

• Rehab to full performance can be lengthy and requires an exercise routine that will regularly stretch the injured muscle.

• Be alert for signs of stress in other areas due to the horse shifting weight to other legs during rehab.

• Anticipate nine to 12 months before the horse can return to his original work level. Setbacks are common, as the scarred areas break down and remodel.

• Liniments or capsaicin rubs and pulsed electromagnetic therapy can help ease soreness and spasms.

Case History
We followed the struggles of a racehorse after suffering damage to the extensor muscles of a front leg. He made it back to racing, but it was a tough year. In fact, the setbacks were severe enough to indicate permanently impaired ability.

While it’s important to limit movement until sufficient scar tissue has formed, you need to start mobilizing the horse as soon as you can, so the scar tissue doesn’t shorten and tighten, making it that more difficult for the horse to regain full range of motion. For some horses, progression from stall rest to hand walking to turnout works perfectly.

But this racehorse was rank enough to want to tear off as soon as the leg started feeling even a bit better, making safe hand walking nearly impossible (heavy sedation was ruled out because of the risk of injury). He therefore was put back into light, controlled exercise.

Things went well for the first weeks, and great care was taken not to overdo it. However, it shortly became apparent that things were far from normal. The horse didn’t stand square up front, preferring to place the injured leg farther behind him than normal. The opposite front leg periodically showed slight signs of filling, and he would often stand off it right after work, both indicators that he was overstressing it.

While he appeared to advance both legs evenly and smoothly, we were suspicious he was shortening his stride on the good leg to match what was comfortable for the injured one. We could also often hear a subtle difference in how heavily he came down on the front feet. The horse remained eager, alert, eating well and interested in his work, however, so efforts continued to gradually increase his work level and speed.

Careful examination of the injury site throughout this period wasn’t reassuring. The laceration area would periodically swell at times for no apparent reason. In addition, the muscle tendons above the injured area often felt tight compared to the other side. Firm palpation over these tendons was uncomfortable for the horse. Ironically, the only time the tendons felt as soft and relaxed as in the normal leg was after the horse had been allowed to extend and work at speed.

He also went through several weeks where the skin over the injured area and above it would sweat. This local sweating is sometimes seen after extensive injuries and probably is related to nerve damage and/or the regrowth of damaged local nerves. It was anyone’s guess as to whether or not this nerve involvement could also have been causing odd sensations or pain.

Treatment throughout this period consisted of daily electromagnetic therapy (Respond Systems Bio-Pulse, www.respondsystems.com, 203-481-2810), topical capsaicin creams and periodic injections of Sarapin, with or without low-dose corticosteroids, over the tight and painful muscle tendons.

The electromagnetic therapy helped control swelling, pain and spasm, as well as areas of secondary soreness in the back or hindquarters. We noted a clear difference in how smoothly the horse worked if electromagnetic therapy was skipped for a few days and a clear improvement when the therapy was resumed.

The horse was racing again just under a year after he had sustained his injury and did well for a while. As expected, his muscular and neurological ability to move the leg normally were intact.

However, the horse soon began to show fetlock problems in the opposite front, believed due to overloading that leg as he protected the injured one.

The trainer decided to see if a few weeks of turnout would help. The horse was put out in a large field where he played with reckless abandon for three weeks. He was observed carefully for lameness, but otherwise no other treatments were used.

At the end of the turnout period, the injury area showed no filling but the muscle tendons felt as tight as they ever had, if not tighter. However, the same problems resurfaced when he returned to work. The horse was obviously pasture sound, but he’d do everything in his power to avoid stretching the injury beyond the point where it was comfortable, which was counterproductive to healing.

This meant we were dealing with repeated cycles of scar tissue being stretched, broken down to accommodate a work level, but shortening up again between periods of hard work. What we needed was a way to keep that muscle on strong stretch/extension without having to work the horse at speed.

We decided to longe him with the injured leg to the outside, forcing him to make it travel through a longer arc. Within a few days, the injury site showed multiple areas of bubbling and filling, but the muscle tendons had softened considerably and the horse was moving comfortably.

He continued with longeing and electromagnetic therapy until the fillings subsided,then resumed work on the track with a dramatic improvement, including a win. He’s longed regularly to keep the injury site well-stretched and continues to train and race successfully.