Small animal expertise boosts treatment of baby horse at UF Large Animal Hospital

When a quarter horse colt born with a severely deformed right hind limb arrived at the University of Florida’s Large Animal Hospital last May, equine veterinarians recognized that traditional methods used for straightening abnormal legs in foals would not work. But today — five months, three surgeries and one small animal surgeon later — the foal is living the good life at home in Palmetto, Fla., running and training on four good legs.

“Traditionally, when you perform an acute correction, you break the leg and then plate it, all at once,” said Ali Morton, D.V.M., an assistant professor of large animal surgery at UF. “In this case, the amount of correction needed would have probably compromised the blood supply and the lower part of the limb likely would have died. There also is a significant risk of infection, which is why these types of procedures often fail in horses, even in the best circumstances.”

Morton then consulted one of her colleagues who treats small animals at the UF Veterinary Hospitals — Dan Lewis, D.V.M., a professor of small animal orthopedic surgery and an internationally respected expert on the correction of limb deformities. For more than a decade, Lewis has used a technique in which the deformed bone is cut surgically, and a device called a circular external skeletal fixator secures and gradually straightens the bone — a process called distraction osteogenesis. The gap that forms between the bone segments fills in quickly with new bone.

“Dr. Lewis has contributed significantly to the literature on distraction osteogenesis, so we called him, and he looked at the foal’s leg,” Morton said. “Our biggest concern was its size, since at 5 weeks old, this foal weighed 220 pounds and was much bigger than your average dog.”

Traditionally in horses, the fixator is pinned to the bone segments. But it quickly became evident that pins were not the answer.

“Within 24 hours, the foal bent some of the pins,” Morton said. “Within 48 hours, he broke one pin. By then, we were at the point of either trying something different, or euthanasia.”

UF’s veterinary team was literally down to the wire – an “olive” wire.

As a last resort, Lewis contacted John Madden from Smith and Nephew, a company that manufactures circular fixators for human patients. The foal’s fixator was made from components used in dogs and cats. Madden provided olive wires, which contain a bead, or “olive,” secured along the wire’s length. These wires, when applied under tension, provided the stability to resist the incredible forces imposed by the 220-pound foal.

Lewis was familiar with the product because he had used this human system to successfully stabilize a fracture in a tiger.

“We didn’t know what would happen, but we were willing to try,” Morton said. She spoke to Anne Prince, owner of the foal, and explained the options.

The Princes own a quarter horse farm in Palmetto, and are longtime clients of the UF Veterinary Hospitals.

“Mrs. Prince said, ‘Let’s try it,’” Morton said. “She said we shouldn’t give up unless things got to the point that the foal was suffering. So we took out the broken pins and put in four olive wires, and over the course of the following three weeks, it seemed to be working.”

Five weeks later, additional surgery was performed, during which additional wires were placed for reinforcement. Serial radiographs and measurements confirmed that the deformity had been corrected and the fracture gap just needed to fill in with new bone.

In time the leg had healed to the point that veterinarians began to stage removals of rings and wires. A CT scan was performed on the foal’s leg, and he remained at the UF Large Animal Hospital until his discharge.

“To my knowledge, this is the first time sequential correction, which employs a circulator fixator and distraction osteogenesis, has been used to correct a limb deformity in a horse,” Lewis said.

Morton credited Lewis and the foal’s owners, the Princes, along with the foal himself for the case’s successful outcome.

“The only reason this worked was first, Dr. Lewis, but also the Princes, who treat all of their animals very well and allowed us to do everything we did,” Morton said. “The foal was also an excellent patient the entire time. He put up with all the bandage changes and antibiotics, took care of himself and never got mad at us for poking and prodding.”

Morton added that although complications had been faced from the beginning, the UF veterinary team and the foal’s owners took “one day at a time” and things slowly improved.

“We’d hoped it would, but in the world of horses, this kind of success doesn’t happen very often,” Morton said.