MY FIRST HORSE SURGERY, by Mark E. Burgess

The first clinical block course of my senior year in vet school was large animal surgery. It proved to be a pleasant change from my prior classes; there were no lectures and no exams, just clinical work, almost as if I were a graduate veterinarian.

Most of the cases I saw during those few weeks were horses referred to the hospital for difficult surgeries. I observed an arthroscopic procedure to clean out an arthritic hock joint, and assisted with an exploratory surgery to remove a large mass in a mare’s uterus. An eighteen-year-old grey gelding presented with a grapefruit-sized melanoma near his anus; we debulked the bleeding mass to provide some relief for the horse. Unfortunately a cure wasn’t in the cards, as the tumor had metastasized to other parts of his body; it was only a matter of time before the aggressive cancer caused his death. His owner knew the end was near, but she was grateful to be able to share a few extra months with her old companion.

Of course, part of the surgical process involved handling patients under chemical restraint. Anesthetizing large bodies that massed 450 kilos (1,000 pounds) or more was a difficult proposition. Patients get dizzy and disoriented during anesthetic induction, that phase where the drugs start to hit the brain and normal awareness begins to fade into unconsciousness. That was fine with a dog; we could hold the animal and provide gentle yet secure restraint. A towering Clydesdale horse was another proposition altogether.

Ingenuity had provided elegant solutions. The bulky surgery table in the main operatory could tilt sideways to a vertical position. When a horse was to be anesthetized it was walked over and lightly strapped to the vertical table surface with heavy leather binders around its belly and chest. A tranquilizer had already been given so that the animal would be relaxed and stand steady.

When the patient was secure in the support harness, an anesthetic drug was given intravenously and the horse would fall asleep still standing in the straps. Then the table was simply flipped to the horizontal position with the animal attached. Surgery could commence with no manual lifting of the heavy body required.

I first saw this process in action when I assisted on a Thoroughbred mare with a mangled forelimb. She had gotten tangled in a fallen barbed-wire fence, suffering two deep wounds plus a score of cuts and abrasions from her fetlock to her elbow. Although she had been treated on the farm, she needed extensive debridement and careful closure of the lacerations to prevent infection and other complications. The extent of the injuries and the mare’s level of anxiety had led the doctors to conclude that general anesthesia was needed.

The technicians led the limping mare into surgery and buckled her to the tilted surgery table. She was a rich chestnut color, her sleek coat highlighting smooth contours. Long legs and graceful lines spoke of speed, and her chiseled face was alert and intelligent. I was no expert on equine breeding, but this horse obviously possessed fine bloodlines.

An IV catheter had been previously placed in one of the mare’s jugular veins, and now a fluid line was affixed to the catheter’s end. The tubing ran to a large glass bottle held in the anesthesiologist’s hand. This held a drug cocktail which was a mix of thiamylol sodium (a fast acting barbiturate) and guaifenesin (a muscle relaxant). Once everything was ready, the doctor turned the bottle upside down and held it high in the air, letting the drugs run full speed down the IV line. A bulky equine body required a lot of anesthetic, and the liquid literally poured from the bottle like water from a tap. In less than a minute the mare’s eyes rolled and the whites showed as she became excited, struggling just briefly in her restraints before losing consciousness and sagging into the harness.

We all breathed a sigh of relief; despite the precautions, there was always a degree of risk when large patients were going to sleep. Anything could happen, and sometimes did, during that brief delirious stage. But this time all had gone smoothly, and the technicians scrambled to roll the heavy table into its horizontal position. When it was locked in place with our patient atop it, we jacked open the horse’s mouth. The anesthesiologist deftly slid an endotracheal tube as fat as my wrist into the open windpipe. The tube was then attached to hoses running to the oversized anesthetic machine standing nearby. The machine was activated and oxygen laced with anesthetic gas began to flow into the mare’s lungs.

Next the technicians inserted a small catheter into the facial artery of the horse. The vessel ran just under the skin of her cheek, an easy target to hit once our patient was immobilized. With the catheter hooked to a monitor, we could take real-time readings of her arterial blood pressure while she was under anesthesia.

Meanwhile, I clipped electrical leads to the horse’s legs and flipped the switch on the cardiac monitor. Now the slow rhythm of her powerful heart became translated to an audible beep from the machine’s speaker. Once we were sure she was breathing steadily and her cardiac rhythm was normal, we shaved and scrubbed the injured areas of the mare’s left forelimb.

Viewed more closely the horse’s injuries were ghastly to behold. The thick skin had been laid open in two deep gashes longer than my hand could span, revealing the pink and red flesh beneath. Crusted blood was matted into the surrounding hair; we shaved a liberal space around the wounds to create a clean work area. I saw white stripes of exposed tendons running within the darker muscle tissue as I gently scrubbed the region with iodine soap.

When the wounds were cleaned, we began the process of debriding the traumatized skin. This involved cutting or scraping away any unhealthy tissue and creating fresh margins that could heal properly. I worked alongside Dr. Brenda Babick, a short, stocky woman in her mid-forties who was one of several resident surgeons. We were assisted by another student, Karen Thomas, as we cleaned and sutured the wounds. The surgeon delegated much of the skin closure to Karen and me, since it was the simplest task at hand. Meanwhile, the doctor had discovered some deeper trauma and a lacerated extensor tendon that needed repair. As I threw my sutures in the skin, I tried to glance over to watch Dr. Babick work. Her hands sped through the delicate closure as if they had done it a thousand times before, and I felt a touch of envy at her dexterity. When she was finished, the two severed halves of the tendon were perfectly aligned as if they had never been apart.

Meanwhile I had my own work to complete, and I pushed myself to quickly suture the large wound that I had been assigned. Proper skin closure is particularly important in the horse. In most species an injury generates a pink healing tissue known as granulation tissue. This slowly fills in any gaps until the wound surface is smoothed over and no deep craters remain. In horses this healing process sometimes goes awry, especially on the limbs. The granulation tissue can grow out of control, developing into huge pink masses that protrude outward like cancerous growths. This excessive regenerative response is known in horseman’s vernacular as “proud flesh.” It could be a nightmare to control, and prevention via proper wound closure was the best medicine. We took care to insure that the skin was sutured securely before we let our patient wake up.

When we were finished, the mare looked almost as good as new. I later heard that she healed well and had no lasting effects from her misadventure. We received a large “thank you” card a few weeks later, complete with a photo of our patient standing in her stall at home. The surgeons posted it on the bulletin board in the hospital office alongside other notes from appreciative clients.

Not all cases turned out as well, however. The most memorable incident during my surgery rotation was also one of the most demoralizing. It happened late on a Friday afternoon in my final week of surgery block. The day had been slow, with only a couple of minor procedures scheduled, and I was anticipating leaving the hospital early. Then around four p.m. the reception desk took an urgent call from a local vet. The referring doctor had a mare in late-term pregnancy that was showing signs of acute colic. He wanted to know if the teaching hospital could see the case immediately. At this stage of my education I understood the need for speed in this situation. Digestive upset in the horse could vary from mild cramping to severe distress. The worst cases might progress to shock and death within hours, even without the added burden of pregnancy. From the description of her symptoms this mare appeared to be in trouble. The hospital advised the vet to send the patient as quickly as possible.

While the horse was in transit the clinicians prepared for her arrival. Dr. O’Brien rounded up several senior students, including me, to assist him with the case. He also found one of the surgeons, Dr. Cutler, and advised him of a possible emergency surgery coming in. Dr. Cutler in turn notified the anesthesiologist and had the technicians prepare the surgery suite. The entire process was quick and efficient, and by the time our patient arrived everyone was ready.

The owners pulled up to the rear of the hospital in a four-wheel-drive pickup truck with a shiny red horse trailer in tow. When the rig was backed up to the admitting entrance of the hospital, it was immediately evident that our patient was in severe distress.

Even before the trailer door opened we could hear the animal inside stomping restlessly and groaning. When the owner undid the latch and the portal swung aside, I caught a glimpse of a jet-black rump. At first the mare was reluctant to back out of the trailer, being too absorbed in her own misery to pay heed to our coaxing. When she eventually decided to move, she came down the ramp in a rush and people scattered to get out of her way.

Exposed in full view she was a beautiful animal, a glossy black Arabian with the delicate facial features and flowing lines typical of her breed. At second glance I realized that she was in fact too shiny; her coat was slicked with sweat. In addition her abdomen appeared tense and distended, more than I would have expected from simply carrying a fetus. Even as I watched she turned and looked anxiously at her belly, and her rear foot came up and kicked at her flank as if to swat away the discomfort there. These were classic signs of colic, although dystocia (difficulty giving birth) was another possibility we had to consider.

Dr. O’Brien talked with the horse’s owner, a ruddy-faced man in jeans and a white polo shirt who introduced himself as Patrick Carroll. I was standing close enough to take in the conversation. The doctor inquired, “How long has she been showing signs of distress?”

The owner frowned and replied, “I noticed her sweating a little and acting restless maybe six hours ago. She’s gotten steadily worse since. I think it’s her gut, as she’s not due to foal.”

“How far out is the pregnancy?” asked the doctor.

Patrick replied, “About 325 days, so she’s close to term, but I really expected the foal next week. My vet took a look and thought her bowel was bloated up.”

Dr. O’Brien nodded and said, “Let’s get her inside and into a chute so I can palpate her. We’ll need some quick diagnostic tests too.”

“Do what you have to, doc,” Mr. Carroll declared. “This little lady is worth a whole bunch, and so is her foal. I’d hate to lose either of them. That’s why I came here instead of having my regular vet try to fix her.”

“You heard the man,” Dr. O’Brien said to us. “Let’s go, people!” With that we all moved indoors to work up our patient.

The mare’s discomfort made her edgy and uncooperative, but we managed to get her into a chute where the doctor could do a thorough exam. A technician took the mare’s pulse and reported it elevated but of low strength. The doctor nodded and donned a palpation glove, basically a clear plastic sleeve with fingers attached that covered his arm from hand to shoulder. After applying some sterile lubricant he slid his hand gently into the horse’s vaginal canal. He continued pushing inward until nearly his entire arm was buried in the mare. She whinnied softly and shifted her feet but otherwise offered no protest. Dr. O’Brien palpated for a moment and then pulled his hand free, saying, “Her cervix is closed; she’s not in labor. I need to do a rectal exam.”

More lube was applied to the glove, and once again the doctor inserted his arm into the horse, this time via the anal opening and up the rectum. He felt around in her abdomen for several minutes, searching for clues to the origins of her illness. He gave a running commentary as he worked. “The fetus is there all right and it’s positioned normally. I just felt a little movement when I touched its head. There’s no sign of the mare pushing the foal back toward the birth canal. Ah…her small bowel feels distended with fluid, definitely dilated beyond normal diameter. She’s tensing up now; the gut is bothering her. Wow, it’s really big. I’m worried about a small intestinal accident such as a torsion. I want to auscult her abdomen and see what I can hear.”

So saying he pulled his arm free and stripped off the soiled sleeve, then grabbed his stethoscope from his pocket. His frown deepened as he applied it here and there on the mare’s belly. Finally he straightened and said, “It’s too quiet in there; I don’t hear the usual gut sounds. Most likely it’s a torsion, but whatever the problem is, it’s not good. Draw blood and get me her blood gases as fast as possible. Someone find Dr. Cutler. Meanwhile let’s tap her abdomen and see what we get.”

The technicians rushed to carry out his instructions, taking blood from the mare in less than a minute and heading off to the lab to evaluate her blood gases. Another tech shaved a spot on the horse’s lower abdomen, and after the area was scrubbed Dr. O’Brien inserted a needle and used the syringe to aspirate a small amount of abdominal fluid.

He held the sample up for us to see. There is always a small amount of free fluid in the abdomen, and normally it is a clear straw yellow color. The syringe contents were cloudy and greenish-tinged, and groans went up from the students as they saw the septic-looking material. The doctor handed the fluid off to be run to the lab for microscopic analysis.

In a couple of minutes Dr. Cutler came walking briskly toward us down the hall. He approached and said, “What have you got, Dan?”

Dr. O’Brien replied, “Acute abdomen in a mare who’s near term. I suspect a small bowel torsion; we’re waiting on her blood gases and abdominocentesis results. But the fluid we pulled looked nasty, and with the way the gut palpates I’d say the bowel’s obstructed.”

The surgeon rubbed his cheek and asked, “No sign of dystocia?”

“Nope. Her cervix is closed; the foal isn’t in the birth canal. I’m pretty sure it’s a bad colic.”

Dr. Cutler nodded. “Well, you know me, I’m a surgeon. I’d say cut her now before she becomes more unstable. This is one of those situations where you’re damned if you do and damned if you don’t. Without surgery she’ll probably die. Either way she could turn sour on us in a hurry. If you want me to go in there, let’s do it fast.”

Dr. O’Brien nodded and said, “We’ll have lab results shortly. I’ll get the owner’s approval and then she’s all yours.” He started back toward the large animal receiving area, while Dr. Cutler hurried off in the opposite direction to advise his surgery staff of the impending procedure.

Within fifteen minutes we had the lab results in hand. The mare’s blood gas analysis showed a metabolic acidosis typical of small intestinal obstruction. With the upper bowel blocked, the stomach’s acid contents had no way to empty, and as pressure built, the acidity had begun to leak into her bloodstream.

The other telling finding was the analysis of the abdominal fluid. In addition to white blood cells, the sample contained rod bacteria, suggesting that septic material was spreading from the bowel into the abdomen. We didn’t have much time before the situation turned deadly.

A short interval later we had the mare in the surgery room and ready to anesthetize. Our patient’s condition appeared to be rapidly deteriorating. She was sweating profusely and her breaths came raggedly as she stomped and fidgeted. The techs had placed a jugular catheter in her neck and had started an IV drip. In addition, they had administered boluses of medications to sedate her and reduce her level of discomfort. Although helpful, these treatments were like dousing a forest fire with a bucket of water. If the mare was obstructed, nothing could stop her downward spiral unless we relieved the blockage quickly.

By the time we were ready, the mare’s pain had her half-crazed. The doctors and techs worked to strap her against the vertical surgery platform without getting kicked. When at last she was secured in place, we took readings on her pulse rate and strength. “Pulse is one hundred and low amplitude,” a technician said as she held her hand to a vein and counted beats on her wristwatch.

“Rapid and weak—she’s going into shock,” the surgeon interpreted. “No surprise there. Get a cardiac monitor on her now, and increase the IV drip rate. Let’s hope that she’s strong enough to withstand surgery.” He nodded at Dr. Reynolds who held the bottle of anesthetic already attached to the horse’s IV line. The anesthesiologist raised the bottle high and the drugs began to rush down the tubing and into the horse.

Things went quietly for about thirty seconds, while the anesthetic took hold and our patient began to relax. As the distress faded from the horse’s eyes, I breathed a sigh of relief. It was just about then that all hell broke loose.

The mare suddenly stiffened and began thrashing wildly in the throws of a grand mal seizure. Her restraints kept her in place, but her limbs were dangerous projectiles and we scattered to avoid the flying hooves. One steel-shod foot caught a wheeled supply table and sent it crashing onto its side, strewing catheters and bandaging supplies across the floor. The horse’s eyes bulged from their sockets and I saw her pupils roll back in her head as she bucked and heaved. The explosive snorts of her breaths and the heavy clanging of the stressed surgery table filled the confines of the room. Even the two doctors were momentarily paralyzed by the sights and sounds of the giant body gone berserk.

As abruptly as the seizure had begun it ceased. The horse went limp and hung flaccidly in the restraints. For a moment or two a deathly silence blanketed the room, and then the technician monitoring the EKG readings called out, “Her pulse rate is dropping.” As he spoke I became aware of the persistent beeping of the cardiac monitor. The tones were slowing, and in addition there was now a disturbing irregularity to the rhythm. The horse’s blocked bowel was altering blood electrolytes and pouring toxins and bacteria into the body. The end result was septic shock and the heart was losing function. In a short time it could cease to pump blood altogether.

In an instant Dr. Reynolds the anesthesiologist leapt into action. He lowered the bottle of IV anesthetic to stop its flow into the mare, shoving the half-empty vessel into the hands of a student. “Give me a tracheal tube!” he exclaimed, grabbing the now unconscious animal’s mouth and yanking it open. Someone handed him a large tube and he said, “I need light!” A tech was quick at hand beside the doctor, shining a small flashlight down the dark throat. The horse was still in an upright position, held there by her straps.

“Someone grab the jaws,” the vet commanded. I quickly stepped forward and obliged. The mare’s flesh felt clammy and cool beneath my fingers, her mandibles slick with drool as I struggled to maintain my grip. I pulled the mouth open as wide as I could, straining to support the weight of the bulky head.

My contribution freed up Dr. Reynolds’ hands. With his left he grabbed the mare’s tongue, pulling it out to better visualize her throat. His right hand then slid the endotracheal tube down her gullet and deep into her windpipe. As soon as it was in place he attached the oxygen hoses and turned on the gas flow.

“She’s ventilated,” the anesthesiologist called over his shoulder as he monitored his charge.

“Good. Let’s get this table flipped quickly,” Dr. Cutler answered. The techs and students labored to rotate the table and lock it in its horizontal position. As they did so the EKG monitor suddenly flat-lined and its beeping was replaced by a shrill alarm code.

The anesthesiologist said anxiously, “Are we losing her? We’ve got no beat!”

Dr. Cutler shook his head as he listened with his stethoscope. “I’m still getting a faint rapid heartbeat here.”

I glanced at the EKG leads as we had been taught. Sure enough, one of the alligator clips lay loose on the table, having been dislodged from the skin as we repositioned the animal. I grabbed the metal clamp and reattached it. Immediately I was rewarded with the return of an audible heartbeat from the monitor.

Our reprieve was brief, however. The techs quickly positioned the mare for her surgery, but no sooner had they begun to shave her when the monitor alarm went off again. This time it was for real. Dr. Cutler listened for a moment at the mare’s chest, then threw off his stethoscope and shouted, “I’ve lost the heartbeat! She’s going down. Hand me a scalpel NOW!”

A student grabbed the blade from the surgery pack, unconcerned about sterility, and slapped the handle into the surgeon’s hand. Jumping atop the table, Dr. Cutler straddled the exposed belly of the dying horse and brought the razor-sharp blade down in a savage motion. The gleaming steel parted fur and flesh as if it were tissue paper. In a scant few seconds he had created an incision the entire length of the mare’s abdomen. Blood welled sluggishly from the wound, no longer driven by a beating heart.

Dr. Cutler grabbed the skin margins with both hands and pulled them wide. Subcutaneous fat bulged out of the gaping hole, followed quickly by masses of dark, bloated intestine. But the surgeon had no eyes for the gut; he was after a more important prize. Pawing frantically through the lengths of bowel he exposed a huge pink structure that bulged roundly from the body cavity. It was the gravid uterus of the mare, and it held a tiny life that might yet be saved.

Again the scalpel flashed, albeit with a bit more caution. Dr. Cutler slit the uterus open along its length, then dropped the blade and reached gently inside. His hands emerged with a fully formed foal clutched in his fingers. It was jet black like its mother and covered with shiny membranes. The doctor laid the limp body on the table next to the mare and called for a towel. One was found, and he used it to strip the amnionic sac and fluids away from the newborn animal.

Dr. Cutler opened the foal’s mouth and wiped it out, clearing the airway. As techs continued vigorously rubbing the tiny wet body, the doctor put his mouth to the animal’s face and blew in its nose. Its thorax expanded just a bit, and then shrank again as the doctor pulled away. He repeated this process once, twice, and then again. Between breaths he called for the techs to bring a small endotracheal tube so that he could intubate the foal.

Meanwhile Dr. Reynolds had his stethoscope out and was listening intently to the infant horse’s chest. His expression fell, and after a moment he looked up at the surgeon and shook his head.

Dr. Cutler read what was in the anesthesiologist’s eyes and the energy abruptly went out of him. He ceased his attempts to ventilate the foal and rocked back on his heels, his shoulders sagging tiredly as he laid the tiny head gently on the table. One of the techs reached over and switched off the heart monitor, killing its insistent alarm tone.

That was how it ended, with the attending students and technicians standing quietly, gazing at the two doctors slumped in defeat amongst the blood and entrails, nothing to show for their efforts but a dead mare and her dead foal.