A contracted tendon occurs when one of the flexor muscles along the back of the leg exerts more pull than normal, forcing the leg to become more upright through the pastern. In extreme cases, the heel is elevated off the ground and the toe points down or back.
A horse with a severe contracted tendon eventually may not even look normal in the affected leg and hoof. He certainly doesn’t stand normally. Usually found in foals, contracted tendons can also occur in horses battling chronic lameness. It’s most often seen in front legs, but it can occur in hind legs as well.
However, the term “contracted tendon” isn’t an accurate description of what’s going on. Tendons can’t contract. Only the muscles to which they are attached contract, which might be what’s going on in the early stages.
A horse takes weight off a painful leg by activating one of the flexor-tendon groups to pull either the ankle or the foot back out of a full weight-bearing position.
One theory is that if the horse constantly stands in this abnormal position, the tendon will eventually shorten permanently. If the flexor group involved is the superficial flexor, the horse will knuckle forward at the fetlock. If it is the deep flexor, the pull will be on the coffin bone and the heel will be brought off the ground. The result of deep flexor tendon shortening, if severe enough, is a club foot. Treatment involves relieving the source of pain, proper hoof trimming and plenty of exercise. For severe cases, surgery may become necessary.
Foals that develop contracted tendons, which may be due to cramped positioning in the uterus or even abnormal activity in the muscles or check ligaments, often basically fix themselves. However, theories about the causes also point to defective sulfur cross-linkages in the tendon and rapid growth spurts.
Rapidly growing horses that are also fleshy and receiving a high-calorie diet with limited exercise do often develop contracted tendons. Some people mistakenly still believe it’s too much protein causing the problem, but it’s really the calories.
The first thing we’d do is cut calories, especially carbohydrates like grain. We’d also use maximum turnout in a large area.
The horse must also receive an adequate and balanced mineral dietary intake, so have a nutritional analysis done if you’re not certain the hay and feed you choose meet these needs. Major-mineral deficiencies and imbalances can both cause contracted tendons. Calcium and magnesium, as well as copper, are particularly incriminated.
Exactly how this nutritional defect causes the problem is not clear, but contracted tendons can sometimes be “cured” by treating young horses with tetracycline. This doesn’t suggest an infection is the cause. The assumed explanation is that tetracycline helps because of its strong ability to bind calcium ions. What this means in term of a mechanism is not clear, but it does establish another link with mineral metabolism.
Vita-Royal’s supplement Untie ($38/lb.) is a blend of both chelated and inorganic calcium and magnesium sources, trace minerals, vitamin E and selenium. Although primarily developed for horses with muscular problems, the product is claimed to also help with contracted-tendon problems.
We didn’t have any foals with severe contracted tendons to try the product on, but we did have two two-year-olds that were clearly abnormal in this department. These two horses were straight through the pasterns, tied in at the knees, and tended to buckle forward easily at the knees.
Sometimes their legs would buckle and “tremble” slightly. We also noticed a somewhat abnormally high muscle tone in general and a tendency in one horse to have spontaneous twitching, usually in the triceps. Nerve blocks up to and including the ankles eliminated foot and ankle pain as a cause. Examination of the knee joints was normal, and knee flexion tests didn’t cause any changes in their way of going.
We gave Untie at the full-recommended dose of five ounces once a day. Within three days, the muscle tone had vastly improved and twitching stopped. By seven days, the knees stopped buckling, and the angle at the fetlocks had dropped two to three degrees. Dosage was backed down to three scoops per day, and the improvements held.
We feel these results, of course, are a long way from proving Untie would work on every case or on more severe cases, but it did convince us enough to try the product when we encounter a contracted tendon.