These deformities are commonly referred to as contracted tendons, even though true tendon contracture is unlikely the cause of the problem. Generally, flexural deformities are divided into congenital and acquired types. Congenital deformities are present at birth, and acquired deformities develop at some stage of the growing period.
Acquired deformities manifest differently depending on the age of the horse.
Many factors can be involved in congenital deformities. Multiple factors may be involved in a given case. Congenital flexural deformities can be due to hyperflexion, or less commonly hyperextension due to flaccid or relaxed flexor muscles and tendons. Some of these deformities can cause dystocia or difficult foaling. Digital Hyperextension Many foals are born with flaccid flexor tendons, such that their toes elevate off the ground during weightbearing.