Amputation and prosthetic legs enable once-doomed horses to live healthy, happy lives

by Denise Steffanus

MOST HORSES with irreparable damage to a lower limb from injury, laminitis, or other disease are euthanized. But it does not have to be that way. A handful of veterinary surgeons have been successful at amputating the damaged portion of the limb and replacing it with a prosthetic leg.

The first such procedure was performed in 1973 when a human orthopedic surgeon replaced a damaged right forefoot on the Lucien Lauren-trained Spanish Riddle with a prosthesis. But perhaps the most dramatic early work came more than ten years later when then-Washington State University veterinary surgeon Barrie Grant, D.V.M., M.S., was faced with the task of amputating the right hind limb of stallion Boitron (Fr) and developing a prosthesis to support the horse.

Boitron's new hind leg

French Group 2 winner Boitron severely injured his right hock during a kicking tantrum on a flight from Los Angeles to Chicago to compete in the 1981 Stars and Stripes Handicap (G2) and to face John Henry one month later in the Arlington Million Invitational at Arlington Park.

Because of the extensive damage, Boitron was retired to Wally Dollase's Rancho Rio Vista in California, where he was syndicated for $900,000. The injury compromised Boitron's blood supply to his lower limb, and over the next few years, problems began to develop with his right hind foot. Dollase called in Ric Redden, D.V.M., a Kentucky surgeon and farrier who is best known for his work with laminitic horses.

"I took the bandage off, and his whole foot--coffin bone and everything--was in the bandage," Redden said. "It was brown and just fell off."

Rather than euthanize Boitron, Redden suggested Dollase send the stallion to Grant to be fitted with a prosthesis.

At Washington State, Grant, mechanical engineer Gary Held, and their colleagues set out to design a prosthetic leg for Boitron, who, because of further problems caused by the damaged blood supply, eventually had to have his lower right limb amputated four inches below the hock.

Responding to a suggestion from one of his barn men, Grant's group modeled the first prosthesis after the stilts worn by ceiling-tile installers and used a Volkswagen steering column from a junkyard for the basis.

"We finally got the design right on the prosthesis, and that took us a long time," Grant said. "The engineers couldn't believe how strong horses are, and they kept under-engineering it. [Boitron] would wake up and twist it off."

Through trial and error, which necessitated that Boitron undergo anesthesia 18 times during the fitting process, the group finally arrived at a workable design.

"When [Boitron] woke up and went back to his stall, he was so proud of himself he would have bred a mare that night," Grant said of the final fitting. "That was in December of 1984, and he was breeding in February ['85]. He would have bred in December, but the season wasn't open."

Boitron was transferred to Old English Rancho in Ontario, California, where he stood two seasons before succumbing to peritonitis on May 10, 1987. During the 1985, '86, and '87 seasons, Boitron sired 60 registered foals, including eventual Grade 2 winner and $504,654-earner French Seventyfive.

Candidate for a prosthesis

Many factors must be weighed before a horse can be considered for a prosthetic limb. The primary consideration is disposition: Will the horse accept the prosthesis and then be intelligent enough to adapt to it?

According to Grant, who now is chief of staff at San Luis Rey Equine Hospital in Bonsall, California, the two most important adaptations after amputation are for the horse to learn to function while wearing the prosthesis and to accept support of a sling during recovery and for subsequent changes of his bandage and the prosthesis.

Grant typically observes an amputation candidate to see if the horse is willing to lie down and get up while wearing a full-limb cast. He then places the horse in a sling to see how the animal will react. How the horse behaves in both situations indicates how adaptable the animal will be to a prosthesis and sling.

"The most adaptable patients are those that have learned to lie down early as a means to reduce the pain and to protect the [opposite] limb from overuse," Grant said. "Many horses actually learn this in the first few days and are ideal candidates for amputation."

Of equal importance is that the horse's opposite limb be sound enough to share the weight equally with the prosthetic limb. Failure to do so could inhibit healing in the stump of the leg wearing the prosthesis or cause the foot of the opposite leg to develop laminitis, depending on which limb the horse tends to use as its primary support.

Grant said qualities of an ideal candidate are:

•Good overall health;

•Soundness of opposite limb;

•Good appetite and normal bowel movements;

•Willing interaction with humans;

•Adaptability to a sling;

•Tolerance of injections and other medical procedures; and

•Intelligence to accept challenges in a calm and rational manner.

Grant also assesses the owners' willingness and ability to provide lifelong aftercare for the horse. Aftercare includes a commitment to daily monitoring of the horse; removal of the prosthesis every other day to replace dressings and then reattach the prosthesis (Redden advocates once a week at the very least); providing the horse with a clean, safe turnout facility; and acceptance that the horse never can be ridden.

Redden enhances procedure

Redden, who had worked with Grant on two amputation cases at his clinic in Versailles, Kentucky, was inspired by the work the Washington State surgeon had done with equine prosthetics, and he set out to improve the state of the art.

"The skin closures were not as tough as I would like to have seen them," Redden said. "They were difficult to maintain."

Due to that difficulty, Redden developed a method to graft pieces of germinal frog tissue harvested from the amputee horse's hoof to the end of its stump as a better way to pad it. The procedure was so successful that Redden adopted it as part of his protocol.

"The whole idea of generating a tougher pad has been the longevity of some of my better cases," he said.

Redden's most enduring case is an 18-year-old mixed-breed mare named Josie, who was the test horse for the first frog-graft procedure, which Redden performed after her amputation surgery in February 1992.

"She's outside 24/7 and if she doesn't want to be caught, you won't catch her," Redden said with a laugh. "She can outrun everything in the field. And she runs three-legged and uses the prosthesis as a balancing pole until she stops, and then she spins around on it and takes off."

Another one of Redden's cases is the Missouri Fox Trotter stallion nicknamed Gideon, who is a permanent resident of the special-care facility Serenity Equine in Evington, Virginia, and has survived nearly ten years with a prosthetic hind leg.

"He covers his mares live, and he doesn't seem to have a problem," Redden said. "The ones that have done well actually are happier than a lot of old, crippled broodmares that I have to see on a yearly basis that are just trying to go from one foal to the next. They're fat and slick, and they rip and run, and they play and do things that the average horse does."

According to Redden, it takes about five months from the date of surgery for the leg to quit swelling and the frog graft to become stable.

"That's about the time when I make a mold of the leg and design the permanent prosthesis, which is a very simple device. It's just a clamshell that snaps on and off," he said.

Prostheses

Prosthetic legs in horses have come a long way from Grant's Volkswagen steering-column stilt. Modern prostheses are made from high-tech materials such as Kevlar, which is used to make bulletproof vests, and are produced through a vacuum-molding process.

First, a negative mold of the horse's leg and stump are made to assure the custom-made prosthesis fits properly. Next, the initial prosthesis is placed on the horse, and Redden observes the horse's movement and comfort level and how well the prosthesis works for that particular horse. During the five months after surgery that the leg is going through changes, the horse is fitted with several temporary prostheses.

Redden has worked for 25 years with Brian Cornish, a retired human orthotics expert in Lexington, to refine the prostheses he uses on his amputees. Redden admits that much of the work is trial and error before they arrive at the best design for a particular horse.

"I'd draw him a picture of the leg and what I wanted to do and how I thought we needed to take this thing off and on, because I knew the horse," Redden said. "He'd say, 'All right. Here are the options: I can do this, or I can do that.' "

After they agreed on a design, Cornish would produce the prosthesis in a laboratory Redden set up for him in his clinic.

"So it's not really anything difficult to do," Redden said. "You just have to have the proper design for the proper leg and the proper horse."

Changing mind-set

The horse industry has been reluctant to accept amputation and prosthetics as a means of saving a horse's life. Grant said he performs only one procedure about every 18 months. "People just haven't accepted it," he said.

Many people consider amputation aesthetically displeasing, sawbones medicine, or torture. Redden has performed the procedure on about 40 horses, and his successful cases indicate otherwise.

"I have lots and lots of amputee people come by to look at my cases, and they think it's unbelievable because they know what it's done for them," he said. "The technology that is out there now for humans is incredible. The Flex-Foot is something I looked at years ago for my patients. With a little engineering change, we could design a Flex-Foot to allow the horse to travel as comfortably as humans do.

"There are bilateral amputees with Flex-Feet who are running marathons and climbing mountains," Redden said. "That whole industry has taken off; it's not in the closet anymore. Amputees in horses are still in the closet. It's been accepted in humans because the mind-set has changed. And that will occur with horses. It's just a matter of time.

"It's incredibly rewarding when you see a horse look over his shoulder at you when you put the leg on, and they give you the feeling like, 'Hey, guy. Thanks. This is pretty good. I like this.' To me it's been a great, rewarding experience."

Denise Steffanus is a contributing editor of Thoroughbred Times who writes frequently on veterinary and farm management topics.