Article by Michael Mahaffey Photos Courtesy Dustin Devine
On and Under the Skin
In addition to upper airway issues, tumors on the skin are the most common conditions Devine treats with a laser in his practice. In fact, it is often his first tool of choice to treat these conditions.
“The laser is beneficial in removing tumors, lumps, bumps,” Devine says. “The laser can be a bigger gun if they fail to respond to resection using a scalpel. The laser often times can be an alternative treatment mode that can crank things up a notch, so to speak.”
Lasers can be used anywhere on the skin to excise growths, even around the eye. The burning energy of the laser does do some collateral thermal damage to tissue left behind when it cuts, but in the case of tumors, Devine says that isn’t necessarily a bad thing.
“You’re cauterizing areas near it and reducing chances that portions of the tumor may be missed and likely spread or recur,” he says. “It also seals lymphatics, blood vessels and nerves that are cut during the procedure. When you’re dealing with tumors, that’s usually how they spread, through the circulatory system and lymphatics. Having those things sealed does a lot by way of preventing or minimizing the amount of cancer cells that are carried away from the wound itself.”
Palmar Foot Pain
Another area where lasers can be used to great effect is in the treatment of musculoskeletal or lameness issues; however, treatment of these problems with laser surgery is usually seen as a last resort option to stop or reduce pain.
“In the area of musculoskeletal ailments, one of the conditions that has afflicted Western performance horses for years is navicular syndrome,” Devine says. “One of the more common treatments for this is a palmar digital neurectomy, and one of the major complications of that surgery is the horse develops painful neuromas from the nerve fiber re-growth after transecting the nerve. This procedure can be made a less painful and the chance of neuroma formation less if a CO2 laser is used to perform the transection.
“The troubling thing about navicular is it’s a progressive condition,” he says. “It’s progressively degenerative. As the horse gets older and continues to compete, these things march forward. It’s kind of like arthritis in its degenerative nature.”
Devine sees using lasers in this type of surgery as a last ditch, salvaging therapy that should only be considered after every other treatment option to reduce navicular, known in veterinary circles as palmar foot pain, has been tried—from changing the way the horse is shod, to rolling the toe to facilitate breakover, using anti-inflammatories such as bute or banamine, then progressing to injections in the coffin joint or navicular bursa. Only then, if a horse is still getting worse, would he consider discussing the neurectomy option with a horse’s owner.
“The thing about doing the neurectomy is once it’s done, it’s an irreversible procedure,” he says. “The horse won’t have sensation to his foot. Foot hygiene on the part of the horse owner becomes an important concern. The horse could step on something, damage its foot and not even know it because they are basically numb.”
Following the procedure, the horse loses the stretch sensors in its ligaments and muscles, as well as the ability to naturally autocorrect their foot placement. A single misstep can catastrophically damage the tendons and ligament in the back of the foot. The horse could also step on a nail or bruise its foot and not even realize it.
Most of the surgeries that Devine performs are on horses that have previously had neurectomies performed by conventional methods, and they are becoming painful again because the nerves on the back side of the pastern region are re-growing.
“The body says ‘Wait, I need to heal this injury,’” Devine says, “and it basically tries to re-grow the nerve. As the nerve re-grows, it can be a painful situation when those nerve fibers begin to sprout and try to regenerate. It’s kind of like an amputee with phantom pain issues once the nerve is cut.”
Devine believes the laser is the best tool to use to re-do neurectomies or to resect neuromas that are causing horses pain because the laser energy seals the nerve fibers themselves during the procedure, resulting in fewer painful sensations following transsection. The laser also slows the re-growth of the nerve.
“I’ve had pretty good success by going back in and revising those wounds and providing neurecomy or neuroma resection by using a CO2 laser,” Devine says. “I think that’s given a lot of horses a little bit longer interval between the time when these conditions develop and become painful again.”
A neurectomy may provide a horse that was maybe once a good athlete but had become chronically uncomfortable a more comfortable existence, but Devine says extreme care needs to be taken with the horse to avoid a catastrophic injury due to the horse not being able to feel sensation in its foot anymore.
“It may be fine to turn them out to pasture,” he says, “but even with that, foot hygiene, picking the feet out, cleaning the feet once or twice daily would be a good idea because the horse could pick up a nail or something like that and not even know it. Then you have a real life-threatening situation, meanwhile horse and owner are none the wiser because he won’t be limping around on three legs.”
He also cautions against riding such horses unless the rider is experienced and knows how to feel the horse and direct it in a way that protects it from hurting itself.
“I would caution someone that this is not a horse you want to take trail riding on uneven surfaces or on rocky terrain,” he says. “I always caution people that no children should ride the horse because it can be a time bomb.”
A native of Weatherford, Okla., Dr. Dustin Devine completed his veterinary education at Oklahoma State University in 2002. After performing a surgical internship at Peterson & Smith Equine Hospital, in Ocala, Fla., he returned to OSU in July 2003 to complete a three-year residency in equine surgery. In 2007, Devine completed the certification requirements of the American College of Veterinary Surgeons and became board certified in large animal surgery. He is currently employed as a surgeon for the equine section at Oklahoma State Center for Veterinary Health Sciences.