Despite recent advances in breeding, nutrition and farm management, musculoskeletal abnormalities are often present in the newborn foal. The most common disorder is lax flexor tendons or flexure laxity. It may be a misnomer to call this problem a tendon laxity, since the laxity (weakness) originates in the muscles rather than the tendons.
Tendon laxity can vary in degree from a slight droping of the fetlock to a severe weakness with the foal walking on the back surface of the fetlock and the toes pointing into the air. Tendon laxity can be present in all four limbs. Though most commonly seen in the fetlock and the pastern, it can occur in the carpus (knee), and it is more common in the rear limbs.
The cause of congenital laxity is unknown. Lack of musculoskeletal stress or tension in utero may play a role in its development. Premature foals are more likely to have lax tendons and foals born without the condition can acquire it if they become debilitated for some other reason.
The diagnosis of this problem is evident on examination of the foal; no special tests are necessary. Flexure deformities are characterized by abnormal flexion with inability to extend the joints of the distal limb. The foal walks on his toe, unable to place the heel on the ground, or he walks on the bulbs of his heels or on the back of the pastern.
No specific treatment is needed in the first week or two of life. Repeated intervals of brief exercise in a small paddock for the first few days of life may be enough. As your foal becomes more coordinated and agile, the muscle tone will increase and tighten the tendon. If your foal is walking on the bulbs of the heels, a light tape bandage may be needed to prevent abrasions. Heavy bandaging and splinting are not needed because this results in disuse of the leg muscles, weakness and increases laxity.
If time and increased muscular activity does not resolve the laxity, corrective trimming and shoeing may be necessary. Often the heels of the foot have overgrown and need shortening. You can do this with a few passes with a hoof rasp. You can also apply a small shoe with a 1.5-inch heel extension to lower the toe and raise the fetlock. Because of the size and softness of the hoof wall, attachment of the shoe to the foot is difficult. Temporary heel extensions can be devised out of tongue depressors and taped to the hoof wall with duct tape. You can also fashion the shoe out of plywood and attach it by wires placed through holes drilled into the hoof wall.
Allow your foal to have controlled exercise. A few hours of turnout in a small paddock daily will help to strengthen muscles. This in turn should tighten the tendons. Check the bulbs of the foal's heels and the back of the pasterns for any abrasions or sores. If there are any wounds, they should be cleaned with a mild soap and then protected with a light bandage such as a sterile 4×4 held on by a piece of duct tape. Do not apply a leg wrap. Support wraps actually increase the laxity instead of improving it.
If the tendon laxity prevents your foal from standing and nursing, then you may have to intervene and help the foal to stand. It is important that the foal receive the mare's first milk, colostrum, which is rich in necessary antibodies for the foal. The foal should receive the colostrum within the first 3 hours of birth.
Currently there is no known way to prevent this problem.