There are several types of leg deformities (commonly know as crooked legs) seen in newborn foals.
Tendon laxity is commonly seen in newborn foals, particularly premature foals. With controlled exercise, this condition generally resolves itself. Controlled exercise includes stretching the muscle-tendon unit, which can include trimming the feet, bandaging to stimulate relaxation and oxytetracyline to relax the muscle. If the limb is hitting the ground, a small bandage can help protect it, but a heavy support bandage will worsen the condition.
Ligamentous laxity is common in newborns but is often self limiting. The legs can be manually straightened but weight bearing can cause crookedness. Controlled exercise will strengthen the ligaments and keep the legs in better alignment.
Tendon contracture (club feet, fetlock contracture, carpal contracture) are a relative disparity between tendon length and leg length. Foals born with contracture should also be checked for undershot jaws, as this would likely indicate problems with iodine levels in the mare. These foals do not respond to treatment as well as other foals. Remember, young foals respond best to medical treatment so do not avoid delaying treatment. In some cases, surgery may be an option. Surgical treatment depends on the site of contracture. If the deformity is not excessive, club footed foals respond well to inferior check desmotomy. In severe cases, the deep flexor tendon may be cut. Fetlock contracture may require cutting of both the inferior and superior check ligaments to allow the superficial and deep flexor tendons to stretch. Surgical treatment of carpal contracture is possible but is generally reserved for select cases. Generally, foals less than one year of age respond best to surgery, but it can also help in adults. Usually, these deformities occur because of premature birth or damage to the growth plate.
Immature cuboidal bones is a dangerous deformity seen in premature foals. The bones are not solid when the foals are born and can be malformed by weight bearing. Foals need to be kept recumbent and/or wear splints or casts when standing so that the bones maintain the normal shape as they solidify. Prognosis is good if the bones do not deform, but the condition is hard to correct if the bones deform. Foals with signs of prematurity should have hock and carpal x-rays taken to ensure this is not a problem. Inflammation or trauma to the growth plate can make one side of the leg grow faster than the other. In foals, the most common version leads to legs that turn out at the carpus (front knee). Fortunately this condition will often fix itself over time. However, hoof trimming and controlled exercise help prevent secondary problems. Periosteal stripping should be considered for carpal versions if foals are severely affected by damage to their growth plate or have not improved by three to four months of age. Other options are available for older foals, but the procedures are more invasive and run the risk for more complications.
Again, it is best to catch these problems when the animal is young. If moderate to severe limb deformities are left untreated, they result in crippling problems as the foal matures and because of the associated pain, most will not become riding horses.