If you see your mare’s newborn filly prancing around the stall like it is wearing invisible high heels, you might be a little concerned that your foal is dreaming of being a ballerina instead of a barrel racer or hunter jumper. But don’t worry; one of the most common deformities that equine veterinarians deal with in newborns is contracted digital flexor tendons. This might cause foals to walk on the toes of their front hooves instead of being flat footed.

Eric Carlson, DVM, equine surgery intern at the University of Illinois Veterinary Teaching Hospital, explains that there are several suspected reasons why this malformation might occur, although there is little hard scientific proof. "One reason contracted tendons might happen is due to intrauterine malpositioning, in which a mare may be carrying a foal that is a bit too large relative to its size," he explains. Other culprits might be ingestion of locoweed and hybrid Sudan grass during pregnancy, goiter, or a dominant gene mutation in the sire.

No matter what the cause, the end result is the same: a tendon that is too tight or too short for the foal’s legs. Anatomically speaking, all horses have two major tendons that run directly behind their cannon bone (the large bone between the horse’s knee and fetlock). They are fittingly named the superficial and the deep digital flexor tendon. Since the deep tendon attaches to a bone inside the horse’s hoof, if it were to be contracted or shortened, it would cause the horse’s leg to curl up beneath itself–which is exactly what happens in a case of contracted tendons.

Veterinarians can correct the de