Contracted Tendons

Also Known As

Flexural deformity

Description

When the pasterns, fetlocks, and/or knees are extremely upright or buckled forward, most veterinarians refer to the condition as contracted tendons. With foals, the cause is usually due to mal positioning in the uterus.

Most foals have wobbly legs when they attempt to stand shortly after birth. The ligaments are lax, and the tendons may seem a little too short or too long. This results in odd leg angles and stances. If the foal is mildly contracted, a few days of exercise and stretching will usually correct the problem. If the problem is severe, a veterinarian should be contacted.

Too rapid weight gain may also lead to contracted tendons. The weight gain causes the heels to lower or mash down, decreasing the hoof angle, and may outstrip the rate of maturation and toughening of the horn of the hoof wall.

A genetic predisposition may lead to the rapid weight gain, slow horn maturation, or both. Injury affecting the fetlock and corono-pedal joints may also cause the horse to go slightly over at the knee and develop contracted tendons.

In older horse, rupture of the common digital extensor tendon may occur for no known reason and contracted tendons may occur secondarily. Clinical signs consist of mild carpal flexion with normally extended fetlocks. The most characteristic feature is swelling over the craniolateral aspect of the carpus.

Symptoms

  • Excessively straight front legs
  • Trembling or instability of one or both fetlocks with eventual buckling of knees
  • Heels lifting from ground so animal is standing on the toe of the foot
  • Unequal horn growth with excessive growth at the heels
  • Weight bearing is placed on toe area leading to damaged hoof wall
  • Shortened stride

Causes

Physiological tendon shortening/contracting is caused by crowding of the foal in the uterus during the last weeks of the pregnancy. In foals up to the age of weaning, contracted tendons may be caused by poor nutritional management with increased protein, unbalanced minerals , and overfeeding.

Discomfort in the foot or lower limb caused by puncture wounds, injuries to the suspensory ligament, or other injuries may also create a withdrawal reflex that causes flexor muscle contraction and altered position of the leg and foot, often causing the foal or horse to go up on the toes like a ballerina. Too much time spent on hard ground or heel pain caused by bruising is often involved.

Prevention

Ensuring that a mare is not overfed and that she receives well-balanced nutrients during pregnancy will help ensure that the foal is born in good condition. Extremes in diet and exercise should be avoided, with careful management of availability of grass feed and other food.

Foals should be checked consistently to make sure that limbs, fetlocks, joints, hoof angles, the horn of the hoof wall, and other features are developing properly. Any injuries should be treated promptly and not allowed to affect the movements of the young horse.

Treatment

Treatment for an affected animal should occur as soon as the problem is observed. If too rapid weight gain is the cause, better regulation of the diet is extremely important. Immediate reduction of food intake by eliminating grain and rich hay and providing the right amount of quality grass hay will help slow weight gain.

Rasping the bearing edge of the hoof wall in the toe area and using shoes with heel wedges to increase hoof angle will be helpful. Although hoof angle in a young horse is greater, it should decrease to the normal 50 degrees by about a year of age as the horse reaches near-mature weight.

Veterinary advice and assistance should be sought as soon as the problem is observed. Specially padded wrap-around splints may be applied to hold the fetlock, pastern, and toe in the correct position. Standing or exercising the foal on a hard surface will aid in stretching the tendons.

Some foals may be helped by an injection of a large dose of oxytetracyline antibiotics. How and why this works has not been proven, but it is believed that the alteration of calcium metabolism or availability in the tendons is involved.

Foals that go straight up on their toes should be kept on soft bedding and given phenylbutazone by injection to relieve pain and inflammation. If not managed early, upright feet will progress to 'club' feet, which may require surgical correction.

In severe cases, including those with older horses, surgery may be the only solution. All horses facing surgery for contracted tendons should have their hoof s trimmed or shod before surgery so that the limb does not have to be handled after the surgery, the bandaging can be properly done, and the horse can walk soon after the surgery. .

Depending on the horse's condition, the veterinarian may shorten the toe by removing hoof wall from the dorsal surface to increase sole depth, maintaining proper alignment to promote normal physiology within the hoof. The horse may be shod with a toe extension to force the heel down, causing the flexor tendon to stretch.

For contracture of the corono-pedal joint, the inferior check ligament is usually cut. For contracture of the fetlock joint and in severely affected foot cases, the superior check ligament and the deep digital flexor tendon may need to be cut. This surgery is not always successful and should be done as a last resort.

Following surgery, hand walking daily for the first ten days for short periods of time is important. As the site of the surgery heals, walking time should be increased. Pressure bandages should be kept on the affected limb for approximately sixty days. Treating the horse with tetracycline is considered to be important by some veterinarians, but no conclusive study as to its value has been conducted.

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