Equine O&P

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Every O&P patient requires an individualized solution, but when that patient also has four hooves, the elements involved with creating a prosthesis or orthosis that will stand up to the rigors of daily use present challenges not typically seen in an O&P clinic. Two of my equine patients are perfect examples of the considerations you need to take into account if you decide to work with this special population.


Luigi came to my wife Linda and me by way of Central New England Equine Rescue (CNEER), Barre, Massachusetts. CNEER asked me to fly to New England from Florida and make a prosthesis for a young donkey with a congenital birth defect. Luigi's right front leg has a nonfunctional hoof area that extends down about three inches below the knee, and he cannot bear full weight on the remaining portion. The fetlock regions on his hind left leg and his front right leg were significantly weakened from trying to get around and needed to be braced. He was also using his nose as his fourth limb for balance. His spine was bowed upward in the middle about four inches higher than it should have been.


Luigi expresses his happiness about wearing his prosthesis. Photographs courtesy of Ronnie Graves.

Linda and I looked at the photos and felt awful. I knew that this little guy's needs would soon exceed what the rescue group could afford, so we formally requested to adopt him. The rescue group had never allowed a long-distance adoption because they like to be able to check on the animals occasionally. However, after checking our veterinarian references and finding out how involved we are in animal rescues, CNEER allowed us to adopt Luigi. We sent a specially modified truck and trailer with one employee and an animal handler to pick him up and transport him from Massachusetts to Florida.

Once home, we devised a sling to raise Luigi off of the ground so we could cast him. Being a typical little jackass, he did not appreciate our efforts at first. Once I had taken the cast, I immediately went to the drawing board to design a device. It wasn't easy. The weight bearing surfaces that he can tolerate are much different from a human. It became a challenge to equalize his weight bearing globally and support him fully without any abrasion spots.

It took four initial sockets to raise Luigi's shoulder to the correct height and bring his spine into proper alignment. We found that a hard-fit socket works best for him. WillowWood, Mt. Sterling, Ohio, donated several Alpha liners to our efforts, and Luigi was appreciative of the cushion it added at first. Over time however, he became more comfortable with the hard socket design and no longer needed the extra cushion the liners offered so we discontinued them.


Luigi relaxes in the pasture and is able to stand comfortably with his prosthesis.

In making limbs and braces for animals, the break-in procedure is the hardest part for the human caregivers to follow. It took Luigi two years before he could wear his leg 23 hours a day. The break-in process I followed with Luigi, and all equines I work with, is a graduated don/doff schedule. The animal wears the device for one or two hours, and then it is removed for two hours. I continue this for seven days and then gradually increase the wear time while decreasing the off time by 15-minute increments. I have found this process helps the animal to accept the device.

The hard work does not stop after the animal has been successfully fit and acclimated to wearing a prosthesis. The human caregivers have a daily responsibility to remove the prosthesis, clean and examine the socket, and clean and examine the animal's residual limb. This is critical to finding an issue, such as an abrasion, before it becomes a serious complication. You never know what you will find. In Luigi's case, if anyone can tell me where in the world he picked up bubble gum on the inside of his socket, I would appreciate it!

Sitka's orthosis

Sitka’s orthosis.

Although Luigi cannot communicate about his prosthesis, we know he is happy about it by the way he acts. If he has to go a day without his leg due to abrasions, or if a stick gets caught in his socket, he stands at the fence, brays his dissatisfaction, and holds his leg out. He really wants his leg on. The true reward of working with Luigi came, however, when we were able to watch him run with a full-sized mule named Spring.


Sitka, an older mare, suffered from a debilitating injury to her tendon at the front right fetlock joint. When a veterinarian came out to possibly euthanize her, he discovered that she was in the late stages of pregnancy. Not wanting to lose either mare or foal, the owners, Jill and Tony Curtis, called me to fly out to Las Vegas, Nevada, and help her. Although she had already had the foal by the time I arrived, finding a solution for her injury was important to allow her to raise him.


Sitka’s orthosis allows her to support her weight and care for her foal.

Sitka's injury resulted in a fixed and bent fetlock joint that could not bear weight, the position of which left her right leg eight inches shorter than her other legs. I created a custommade device that took all of the weight off of the fixed and bent fetlock joint and transferred it above and below her knee. Using Becker Orthopedic heavy, stainless-steel polycentric knee joints, and making sure they were square, I was able to replicate the true motion of her knee. To address the eight-inch discrepancy, I used an old urethane exoskeletal ankle block and laminated the whole device with E-R Resin, which is the only epoxy resin I have found that is strong enough to support a 1,200–1,600 pound animal. I also placed a rubber sole on the bottom of the device to provide traction. I have used this solution successfully with other horses as well, such as Aaron, whose quality of life was extended for an additional eight years during which he wore three of my devices.

Equine O&P care is an emerging field, and the door is wide open for those who want to help. However, not every animal is a good candidate for O&P care. Time, money, and commitment are all factors. This is not a quick fix; the human caregivers must accept responsibility for the animal's care. Remember to check with the treating veterinarian before working on an animal, as most states have regulations that may prohibit working on your own. If you want to have a strong working relationship, work and communicate with the veterinarian; involve him or her in your decision-making process. Most veterinarians I have met are willing to listen and keep an open mind.

Animals cannot verbally tell you where they hurt, but if you watch their body language, you will quickly be able to learn if you've helped or hindered them.

Ronnie N. Graves, BOCPO, LPO, CO, RTP, is the owner of Prosthetics Research Specialists, Bushnell, Florida, and has worked in the O&P industry for 33 years. He specializes in hard-to-fabricate devices and teaches fabrication techniques. Graves is also president of Sumter Disaster Animal Response Team, Bushnell, a non-profit organization that specializes in assisting in animal rescue, particularly in disaster situations.

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