Surgery for a roarer

The surgery to correct laryngeal hemiplegia---roaring---is safe and effective. But it’s scary when it’s your horse under the knife.
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The surgery to correct laryngeal hemiplegia---roaring---is safe and effective. But it’s scary when it’s your horse under the knife.

Cory, my feisty off-the-track Thoroughbred, is all sparkle and spice. Normally, he can gallop the length of a 20-acre hay field without drawing a deep breath. But one day he started huffing and puffing at an easy canter. I had to push him forward instead of holding him back, and his whirl-buck-bolt quotient dwindled. He was less spunky in his paddock, his coat was a little dull, and he was a tad underweight for his 17.1-hand height.

pony

Worried, I asked Jeffrey Warren, DVM, an equine veterinarian in the Rocky Mountains for 40 years, to investigate. Warren listened to Cory’s heart and lungs, palpated his larynx and jugular vein, assessed airflow and discharge from his nostrils. Finally, he listened to Cory breathe at work and at rest.

All signs pointed to laryngeal hemiplegia (LH), a disorder commonly known as “roaring” because of its main sign---heavy, raspy breathing. If your Latin’s rusty, LH refers to half paralysis of the larynx. Located at the throatlatch, a horse’s larynx allows air to enter his windpipe. Cartilage on either side of the larynx opens when the horse inhales and closes as he exhales.

LH occurs when cartilage on one side of the larynx cannot open. Often the paralyzed cartilage is sucked inward on inhalation, further obstructing the airway. In severe cases, the resulting rattle of breathing can be heard from across an arena. Because the horse cannot get enough oxygen, another sign of LH is poor performance---abnormal fatigue when exercised, resistance to flexion and reluctance to work.

Warren recommended a resting endoscopy to look at Cory’s larynx. For the procedure, a long tube capped with a light and camera is threaded up the horse’s nasal passage. The camera transmits images to a computer screen, where you can watch the larynx open and close as the horse breathes. The test continues while the horse is standing quietly, after he swallows and while one nostril is covered.

The resting endoscopy showed that the left side of Cory’s larynx didn’t even flutter when he breathed; it just hung there blocking half his airway. LH is graded from 1 (normal breathing) to 4 (total paralysis), and Cory had Grade 4, which meant his breathing ability was reduced by 50 percent when he was standing still. We live at 6,500 feet elevation; there’s barely enough oxygen for any of us up here, even at full intake. No wonder the big fella was tired.

Further diagnostics would be needed, Warren said, but surgery to alleviate the blockage was the best bet. He phoned the nearest equine hospital that has a surgeon specializing in upper airway respiratory disorders: Colorado State University in Fort Collins. It’s about 450 miles away on narrow, twisting mountain roads.

I winced when Warren started talking price, assuming the cost would fall into the middle five digits and I would have to say no. Instead, he estimated $2,500 for a week’s hospital stay with 24-hour monitoring, a dynamic endoscopy and bronchial lavage, all anesthetics and medications, a full out prosthetic laryngoplasty (surgery on the larynx), and a ventriculocordectomy (removal of the vocal cord) by diode laser. The syllables alone should cost more than that!

TO THE HOSPITAL

A week later, Cory and I hit the road. Day One was slow, mostly two-lane roads, but passable with an Ivan Doig audiobook. Day Two was better until we hit Denver.

Now, I’ve done my share of freeway driving---nine years in Los Angeles--and I can handle a horse rig. But the eight lanes of I-25 narrowed as we delved into thick traffic, and a crosswind was howling. My bumper pull---extra long and extra tall to accommodate Cory---swayed like a kite. Then there were the construction detours, poorly marked interchanges and a posted speed limit that was a comedy. We were caught in a conglomeration of semis speeding at 85 mph bumper-to-bumper, peppered with the occasional RV poking along at 40 mph in the fast lane. Perhaps in solidarity with my horse, my larynx felt tight.

At last, we arrived at CSU’s James L. Voss Veterinary Teaching Hospital, a facility that treats all animals, from abyssinians to zonkeys. A gang of alpacas greeted Cory with the collective stinkeye as he unloaded. He blew in response but stepped into the equine breezeway with his dignity intact.

I met Eileen Hackett, DVM, PhD, who would be doing Cory’s surgery. An eventing rider who did her internship in Lexington, Kentucky---the heart of Thoroughbred country---Hackett told me she finds soft-tissue surgery “challenging and rewarding. Great mentorship in my early career gave me a deep appreciation and love for this specialty.” I knew Cory would be in good hands.

But before surgery there was one more step: dynamic endoscopy, in which the horse’s larynx is viewed while he works. Half of horses with intermediate grades of LH produce normal resting endoscopies. As many as 56 percent show multiple abnormalities on dynamic evaluation, requiring different surgical techniques. Some horses with LH never roar, and some roarers do not have LH. Hackett explained, “The dynamic endoscopy has really been a game-changer for us. It helps us to understand each horse’s specific problem, and then we can tailor the treatment for that.”

Dynamic endoscopies can be done on a treadmill while the horse gallops toward a stationary handler. But this unnatural process excludes the rider’s weight, ignores issues of footing and tack, discourages flexion and precludes changes in direction or pace---all factors that alter breathing.

Overground dynamic endoscopy is today’s money shot. It is conducted without sedation while the horse is ridden. My eyebrows rose at the idea of riding a hot horse with a scope inside his face. Cory, for all his good qualities, is high-strung and oversensitive. Without sedation, nobody gets a needle near his legs, let alone a foot-long tube up his nose. I voiced my concern to Hackett and we came up with a plan.

With my permission and under Hackett’s supervision, Cory was twitched and the nasal tube inserted. The other end of the tube was fastened to a saddle-pad transmitter that sent a wireless signal to a computer screen. Then I climbed into the saddle. To my surprise, Cory performed like a gentleman at all gaits. But his breathing brought to mind an obese smoker climbing a 14,000-foot peak.

The results verified Warren’s diagnosis of Grade 4 laryngeal hemiplegia. Hackett walked me through the video, placing a ruler down the centerline of Cory’s exercising larynx. With each breath, the paralyzed cartilage and sagging vocal cord were dragged into his windpipe. His airway was occluded by 70 percent at work.

THE PROCEDURE

The dynamic endoscopy confirmed what the veterinarians had suspected all along: Cory was a prime candidate for prosthetic laryngoplasty, the installation of permanent sutures to hold the paralyzed portion of the larynx open. Specifically, the arytenoid cartilage that opens and closes the larynx is stitched to the cricoid cartilage, creating a fixed opening on the left side. The arytenoid cartilage on the right side continues to function normally, opening and closing with each breath.

First attempted in 1893, prosthetic laryngoplasty has undergone refinements for the last 125 years. Success rates for the procedure vary from 5 percent to 95 percent, depending on many factors: breed, use, definitions of success, prosthetic material, variations in technique, owner compliance, recovery procedures and rehabilitation methods. But the factor of greatest importance is surgical experience with prosthetic laryngoplasty, and Hackett has that in spades. She does six of the procedures a month.

Still, Cory’s surgery was daunting to me. The worst part was seeing him unconscious on a gurney. He was lying immobile on his side, thick ropes binding his feet together at the pasterns, legs wrapped in heavy plastic, tongue dangling a half-foot out the side of his mouth, eyes glazed and wide open, seeing nothing.

I watched as the surgeon, residents, technicians and upper-level veterinary students prepared his body, their hands approaching and retreating in quick movements like bees to a hive. A plastic tube the size of a drainpipe pumped oxygen and anesthetic into his airway, and the endoscope was threaded up to the larynx. Hackett could see her maneuvers magnified onto a computer screen as well as through the four-inch incision she carved into Cory’s throat.

The delicacy of the larynx’s location cannot be overstated. Within two square inches lies the machinery for breathing, eating, drinking and circulating blood between heart and brain. The arytenoid cartilage is buried in soft tissue, and the cricoid cartilage takes different shapes among individual horses, so surgeons never know exactly what they will find.

The prosthesis must manipulate every breath the horse takes for the rest of his life, sleeping or racing, tranquil or hysterical. That’s about 20 years, given that most larynxes are corrected before maturity. Prosthetic sutures undergo forces of 10 pounds per swallow---and a horse swallows more than 1,000 times daily. With each cough, the prosthesis is pressured even more. If it’s a little too tight or a little too loose, it will fail.

Hackett retracted tissue layer by layer until she reached the larynx, then she sewed fat blue sutures from the arytenoid cartilage to the cricoid cartilage, tying the larynx open. She calibrated the tension on each suture, observing from multiple angles, testing and retesting. When she was satisfied, she replaced various tissues, then stitched the inner and outer sides of the muscle in Cory’s throat. Finally, she sutured the skin closed. The cutaneous stitches would be removed in two weeks; the inner and outer subcutaneous stitches would dissolve. The royal blue prosthesis will remain inside Cory’s throat for life, shining in a neon color that no one will see. After about an hour, the surgery was done. Cory still stared without sight as he lay inert on the table.

ABOUT THAT VOCAL CORD

After he recovered from the sur-gery, Cory had to undergo one more procedure before we could go home. The vocal cord is normally held under tension by the same cartilage that fails in LH. Now that the cartilage was not functional, that vocal cord could be removed. This would open Cory’s airway further and reduce the harmless breathing noise that can persist after a prosthetic laryngoplasty. He would still be able to whinny using the intact vocal cord on the right side of his larynx.

So two days after his primary surgery, Cory the Brave stepped into the stocks for an endoscopic laser ventriculocordectomy. The computer screen showed his handsome new larynx as well as the vocal cord that drooped across it. Through the endoscope, Hackett and her team inserted the long flexible tip of their diode laser, a tool that has revolutionized human and animal medicine. Watching the endoscopic screen, surgeons laser tissue out of internal areas without external incisions or general anesthesia.

As Hackett separated the vocal cord from its moorings with her laser spark, smoke seeped from Cory’s nostrils. I’ve heard difficult horses called “fire-breathing dragons,” but this was a first.

“Couldn’t the vocal cord have been removed while Cory was under general anesthesia to rebuild the larynx?” I asked. “Yes,” Hackett said with a twinkle in her eye, “but we didn’t want to blow him up.” She explained that inhalant anesthesia contains flammable oxygen. And the laser spark … Aha. Tense until that point, we all laughed in comic relief at my inadvertent suggestion of blow-torching Cory’s throat.

Hackett and her resident continued moving the laser in tiny brush strokes to cut away the vocal cord and surrounding tissue. As they burned, they held the tissue tightly with little tweezers---er, bronchoesophageal grasping forceps---that reached all the way up Cory’s nose and into his throat. Vocal cord tissue is tough, requiring a tight hold and an hour of laser ablation. In the end, Hackett fished out a lump of tissue about a quarter-inch wide and an inch long. It looked like raw steak with a line of gristle down one side.

TIME TO GO HOME

After a week of hospital care, Cory was released. The final bill came to $2,796, including unexpected costs for a near-colic following general anesthesia. Both of us were tired, hungry and weak.

Hackett told me that Cory must eat from ground level for the rest of his life. This reduces the chance that he will inhale particles of food through the open larynx and into his lungs. Irritants like dust and ammonia must be avoided. For the next six weeks, he would need multiple medications several times daily and would have to be kept in a stall and hand-walked slowly for 10 minutes twice a day. I explained that Cory is more likely to relax with access to his small paddock--indoor confinement agitates him. Hackett consented.

Still, she warned, Cory must not move faster than a calm walk for six weeks, emphasizing that “the area needs time to heal and scar down to become secure.” She added that quiet recovery prevents complications related to anesthesia, surgical location and the size of the prosthesis. All of which sounds great, but keeping an off-the-track Thoroughbred calm is like telling a bird not to fly. I explained that “Excitable” is Cory’s middle name, glancing toward him as we talked. There he was, a gentle giant rooted in his hospital stall, regarding us with the soft eyes of equine forgiveness, the epitome of Zen. But Hackett smiled in understanding and said, “Just do the best you can. We see everything under the sun as far as activity. Some of it is intentional, which is the kind of activity that makes me cringe the most.” Cringe-worthy activity includes riding the recovering horse, exposing him to turmoil, giving him freedom to run, or chasing him around to see if the surgery worked. Apart from such foolishness, Hackett recognized that animals sometimes react in ways that humans cannot prevent.

THE STOPOVER

Cory and I headed for home with an eight-hour drive through the Rockies on the first day. Already worried about transporting a sick horse, problems expanded in my mind. Every turn was too tight, every downhill too steep, every stop I expected to see my horse strangling on the one mote of hay that I missed when vacuuming the manger. We rounded blind curves only to encounter elk in the road, tourists snapping photos on highway centerlines, oncoming traffic in our lane. As my cursing became more inspired, the cab of the truck glowed as blue as Cory’s prosthetic sutures.

And so, it was a huge relief to reach our overnight spot near South Fork. Full of open meadows and golden aspens in twilight, the ranch is backed by Wolf Creek Pass all sifted with snow. The pens were large, quiet horses stood nearby, and the pipe fencing was safe. Maybe, I thought, we’ll finally get a good night’s sleep.

Then I spotted the footing---the entire pen was mired in manure. Even the owner blanched when she learned that Cory was sporting a week’s worth of needle holes and a cut throat. I explained that he must eat from ground level. She gestured weakly to a barrel feeder about waist-high. He had nowhere else to stay, so I shoveled a clean circle of ground for hay and hoped that the armory of antibiotics in Cory’s body would do its job. I then headed for the nearest motel.

When I returned at dawn, two horses were galloping in the distance. Oh, no. Cory and a cute mare who arrived in the night were racing each other along the fence line. Hackett materialized in my mind with both eyes shut tight and her hand to her forehead.

After futile attempts to corner Cory, I finally managed to get hold of him. He was sweating and shivering, flanks heaving with exertion and excitement. This was far from the “sterile” and “calm” environment in which my horse was supposed to receive his morning medications. It wasn’t even the first thing that had gone wrong that morning: At the motel, I had shaken Cory’s sulfa pills with water in a syringe held shut with my thumb. Goop spewed out all over the sink and down both arms. Severely allergic to sulfa and cognitively exhausted, I had reasoned that it was OK if I died because somebody would come and get Cory. Things went about as well as you’d expect, given our collective emotional state. Cory wiggled while I spoke softly and tried to administer Banamine. I pressed the cold plunger. Nothing. I pressed harder, gritting my teeth. It went straight in---hooray!---and straight out the other side. I tried a second dose. That one slid onto his tongue, and he spat it down my shirt. The syringe of sulfa was next. Shrieking with whinnies, Sassypants next door continued to run back and forth, and I was bathed in my second sulfa shower of the morning, white slop on my face and anaphylactic shock on my mind.

On we moved to the sterile throat spray, which had to be delivered though Cory’s nostrils. Cory waved his head back and forth, evading my hand in perfect 6/8 rhythm. Three times, I threaded the tube into his right nostril only to have him knock it right back out. In a moment of clarity, I realized that my resolve was doing more harm than good. Warren had already offered to help with medications once we were home. I flung the syringes into the truck, angry at myself, loaded Cory and climbed into the cab, emotionally spent and speckled with Banamine paste, sulfa slop and throat spray.

Hackett and Warren were alarmed when they heard even the condensed version of Cory’s antics. Warren had seen Mr. Zen’s propensity for explosion firsthand and agreed that we must provide an artificial means of quieting him for the next six weeks. Hackett recommended valerian root over long-acting pharmaceuticals.

RECOVERY AND RESTORED HEALTH

Most horses cough while eating and drinking as they adapt to an open larynx. Such coughing is usually harmless, though pneumonia can develop from chronic aspiration. Cory’s coughs diminished over the first two weeks. Soft rapid coughs after drinking lasted longer and still occur occasionally. A ground-level water trough helps.

As predicted, keeping a post-operative horse calm is the biggest challenge. A good supply of grass hay or a ground-level slow feeder gives the horse something to do. Stable him near quiet familiar buddies. Routine is comforting, so set a schedule for daily activities. Finally, find qualified help. The demands of major equine surgery and recuperation are ruthless.

Six weeks after surgery, we stopped the valerian and Cory revved his engines within 24 hours. Warren conducted a follow-up endoscopy---unsedated, so let’s just say it involved white knuckles and pale faces---and texted a video of Cory’s larynx to Hackett. Both veterinarians were pleased with the outcome. The laryngeal opening had relaxed slightly, as expected, and there was no sign of inflammation or infection. The prosthesis was intact despite our melee in South Fork.

We began rehabilitation, increasing hand-walks and working up to longer sessions. Lack of exercise always causes tissue to weaken---even bone takes a hit---so I turned up the dial very slowly to prevent injury. No one wants to put a horse through major surgery only to see him pop a tendon. If rehab goes well, it will be six months before Cory is jumping courses again. Today, his coat shines, his eyes are bright and the whirl-buck-bolt quotient is waxing, to my simultaneous joy and dismay.

Hackett emphasizes that new developments make prosthetic laryngoplasty less risky and more effective all the time. To reduce the risk of general anesthesia, Norm Ducharme, DVM, pioneered a standing version of the surgery that requires only sedation. Eric Parente, DVM, initiated the use of ankylosis to stabilize the joint from which the laryngeal cartilage extends. Ankylosing involves roughing up the joint chemically or mechanically so that it heals with arthritic stiffness, making the prosthesis more stable.

Jonathan Cheetham, PhD, is working on nerve grafts and laryngeal pacemakers. In grafting, nerve growth factor is applied to laryngeal nerve to encourage it to regenerate. This technique requires 16 to 20 weeks of recuperation, too long for many racing Thoroughbreds. Still, it holds promise for further development. Laryngeal pacemakers involve implanting an electrode that stimulates contraction of the cricoarytenoid muscle. This contraction allows the muscle to move the cartilage that opens and closes the larynx.

Laryngeal hemiplegia can be corrected at relatively low cost and with frequent success. If surgery is not an option, Warren asks owners to remember that an untreated roarer is “capable of living a useful life and does not need to be euthanized. Instead, have compassion for the animal and change your expectations to allow the horse an easier life.” A roarer can’t race or jump or spin any longer, but he can still walk on flat trails, pony young horses or teach beginners to ride. 

This article first appeared in EQUUS issue #470, November 2016.Save