Angular limb deformities is a condition in which the horse's legs are bent inside or outside by more than five degrees when looking at them from the back or front. These deformities can either be evident immediately after birth when they are called perinatal abnormalities, or they can develop as the horse ages when they are called acquired abnormalities. It is important that all foals be examined by your veterinarian immediately after birth to check for deviations in the lower legs, especially any premature foals or any foals that are born weak. Although a minor 5-degree deviation is normal, any larger angle of the joints should be investigated.
In many of these cases, stall rest for three to four weeks to allow the bones to mature is all that is required. Some of these foals may have normal bones but have deviated joints.
If you have a foal that is premature or weak at birth, it is especially important to have them examined because some foals will have bones that are not completely formed in the carpus and hock. If the bones are not formed correctly and the foal is allowed unlimited exercise, the bones can collapse and the foal will develop arthritis that will be a problem from now on. Exercise may cause severe injury and collapse of these bones can cause permanent damage. If the bones are immature, a cast can be applied until the bones mature, and usually these foals will be fine.
Acquired angular limb deformities occur as the foal grows and Drs. Witte and Hunt indicate in Equine Veterinary Education that trauma and genetics play a role in this condition. All foals that develop deviations in their legs should be examined by a veterinarian. X-rays will be required to determine the severity of the condition and will help determine a treatment plan. Some foals will only require confinement while others will need surgery to accelerate or retard growth, depending on the type of deviation. Regardless, these procedures must be performed early so it is important to have any foals with deviated legs checked early.
Do not include the fetlock and pastern in any bandages in a foal for problems higher up in the leg. Including the fetlock and hoof in a foal's bandage will cause the muscles and tendons to become weak; when the bandage comes off, the foal will not be able to support weight on the leg and will walk on the back of the fetlock. This can cause severe damage and infection to this area. There are several surgical procedures that can be performed if stall rest and bandaging are not effective in straightening the limb. These can be performed later except in the fetlock where surgeries for straightening the leg must be performed at two months of age.
There are several successful surgical procedures that correct these deviations. However, for maximum effect the surgeries must be performed while the legs are growing. These procedures must be performed when the foal is quite young so it is important to have any foals with deviated legs checked early.