Tendon contracture and laxity problems in foals common, but still serious

Tendon contracture and laxity problems in foals common, but still serious

Jun 01, 2003

Tendon contracture and laxity in foals is not an uncommon problem and one that most equine practitioners routinely deal with just about every foaling season.

There always seems to be at least one foal that is born with one of its parts too tight, too loose or somehow out of place.

This foal, born with tendon contracture, has the typical "windswept" appearance with curvature of the back, hips, stifles and hocks.
Contracted tendons are the most potentially serious problem while excessively loose or lax ligaments are probably more commonly seen. These conditions usually involve the ligaments and tendons of the lower limbs, but potentially any such structures in the body can be affected. Occasionally foals are born with such a collection of contractures through their legs and upper bodies that they literally resemble rubber Gumby horses hit by a stiff wind.

These twisted foals are in fact referred to as "windswept" and, though most grow out of the condition, their early management can be complicated by their problems.

Ears, noses, tongues and tails have also all been reported to have suffered some degree of contracture or laxity in young foals. Most owners are quite concerned about the abnormal appearance of their recent arrivals and an explanation and treatment options are usually sought.

Contracture of the front carpi (knees) in this foal was severe enough at birth that it could not stand and nurse. Additionally this foal had severe laxity to the hind fetlocks. The foal was bottle fed for the first week of its life. It was treated medically with intravenous oxytetracycline and splints were applied to the front legs. Within 10 days, the foal had responded well, and the front legs were almost normal. Resolution of the forelimb contracture allowed the foal to begin vigorous exercise which helped the hind fetlock laxity disappear.
Uterine malposition Uterine malposition is the most common reason given for these congenital contractures and laxities. There is restricted space in the uterus, and some foals become twisted or "stuck" in awkward positions that do not allow them to stretch their limbs and move about. These abnormally positioned legs develop tightened or shortened ligaments and tendons.

This explanation is reasonable for contracture, but does little to explain laxity. Occasionally, some foals may be born with both contracture and laxity, which makes the pathogenesis of these conditions even harder to explain.

"Uterine malposition is the most plausible explanation, and the one most readily accepted by clients," says Dr. Andrew Parks, professor of surgery at the University of Georgia College of Veterinary Medicine. "However," adds Dr. Parks, "it is the explanation that is probably the most difficult to support from a research standpoint." Many veterinarians now believe that there are a host of factors, many probably interactive, that all contribute to cases of congenital contracture and laxity. Veterinarians seeking to assist their clients in determining the causes of these problems and in reducing the chances of reccurrence in breeding programs, need to be complete in their investigation of other possible factors.

Plants and toxins Numerous case reports in the literature describe tendon contracture in foals born to mares that were exposed to various plants and toxins. Locoweed, Sudan grass and other plants have been reported.

Though this foal had some difficulty initially, it stood and nursed unassisted. The foal was managed conservatively with simple exercise, and the condition resolved within one week.
Various infectious agents have been implicated, but much more research needs to be done before a definitive link can be made to any particular disease. Contracture and laxity problems have been suggested to be caused by depletions and excesses in various vitamins and minerals in the diet of pregnant mares. Again, no definitive correlation has yet been made. Pathologic bone problems leading to abnormal tendon development is believed likely as well as the existence of various defects in elastin and collagen production.

Genetics may be more of a factor than was previously thought, and there is hope that new advances in gene mapping will shed some light on the exact reasons for the development of contracture and laxity. Until then, it is important to control those factors that have already been identified and to aggressively treat these twisted foals when they occur.

Weak flexor tendons Many foals are born with flaccid or weak flexor tendons. The hind feet of these foals are usually affected, though the front feet can be involved as well.

The typical foal is bright and alert, but when it stands it places the palmar (plantar) surface of the hoof on the ground and the toe does not bear weight. In severe cases, the caudal surface of the fetlock may actually contact the ground.

This foal is wearing a PVC toe extension that has been shaped for the foot and applied with acrylic glue. The extension will force stretch the ligaments and tendons and can help resolve many cases of contracture. These extensions are easy to fashion and apply with some experience.
The majority of these foals self-correct in a few days. Exercise is important and is often directly correlated to tightening of these affected tendons and a return to normal alignment of the fetlock and the bearing surface of the hoof. Trimming, to provide a flat bearing surface on the foal's heels, may be necessary in prolonged cases.

There is a relatively rare condition of extreme laxity in the interphalangeal joints of young foals. The cause of this condition is unknown, and these foals do not respond to treatment. Dr. Ted Stashak, professor of surgery at Colorado State University College of Veterinary Medicine, advises that the only way to differentiate this rare condition from the more commonly seen laxity is to monitor improvement in each foal. Digital photos allow an accurate measurement of angulation changes so that even very slow positive improvement can be noted.