Part of the Developmental Orthopaedic Disease complex. See Angular Limb Deformities and Contracted Tendons.
These show up as either excessive flexion or extension of a joint or joints, usually the pastern, fetlock, and knee and occasionally the hock joint. They may be congenital (present at birth) or develop withing the first few months of the foals life and involve tendons appearing to be either too tight or too slack.
Foals developing the condition are often growing rapidly and on a high plane of nutrition or undergoing a growth spurt driven by a high energy intake. Treatment with padded splints to hold the affected joint in the correct position, coupled with appropriate exercise regimes is often sufficient to correct the problem. Care is needed to monitor splints for chaffing. Sometimes specially prepared surgical shoes or toe extensions made from PVC pipe and attached to the hoof with glue can help stretch the tendon beneficially. When treated early, most cases will resolve in a few days. In more severe or intractable cases surgical correction by means of a procedure known as the check ligament desmotomy may be required.