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 deformity in many ways, but each case requires individualized treatment. Fortunately, "the prognosis for a foal born with contracted tendons is good," Carlson said. While some minor cases might not need any treatment, more severe deformities require intervention.
One of the treatment options veterinarians can try is an intravenous antibiotic. While the thought of using an antibiotic for a problem other than an infection may sound perplexing, "it is thought that the drug prevents the influx of calcium ions into the muscle fibers and brings about relaxation," Carlson explained. And relaxation is exactly what the doctor calls for if tendons are pulled so tightly that the hoof cannot touch the ground appropriately.
Other options include using toe extensions that help to change the break over point of the hoof and stretch the tendons, as well as splints or casts. In a few rare cases surgery is needed to correct the problem, but that is usually more common with the acquired deformities, not the congenital ones.
It is important to note that if a newborn foal has a difficult time walking, it will need human assistance every few hours around the clock to stand and nurse. Although Carlson knows all too well that sleeping on a straw-floored stall for a few nights with a newborn foal might not be the most comfortable bed, the reward is priceless. Watching what was once a crippled filly take her first few steps to nurse without human assistance is worth the wait--even if it does happen at two in the morning.--Ashley Mitek
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.