The Hippo with Toothache (29 page)

We knew right away whom to call: our consulting neurosurgeon, Dr. Mitchell Harris. He might be able to realign those two bones surgically and allow the pinched nerve tissue to heal. If anyone could give Sally a chance to recover, he could. I dialed him immediately.

Like most zoos, we kept a long list of specialists—a mixture of veterinarians and physicians—willing to help us out with difficult cases. The choice of whether to call a human or an animal doctor depended largely on the problem. In this case, we called a physician because of his exceptional skill. Dr. Harris was simply the best in the region at dealing with spinal injuries in any species, human or otherwise.

Luckily for us, he was in town and available. With his usual enthusiasm, he offered to help us organize what we'd need to work on the injured kangaroo. Though he directed an orthopedic trauma and spinal surgery center for humans, it didn't seem to matter that this new patient had four legs and a thick
tail. Within hours, we had assembled an entire team of specialists and equipment and scheduled the surgery for the next morning, which would allow the kangaroo time to stabilize and the experts to gather.

Early the next morning, Sally's condition appeared about the same—neither worse nor better. She'd spent a quiet night in our intensive care unit in a small, warmed cage. To reduce the swelling in her spinal cord, we gave her intravenous fluids along with some steroids. Unlike a healthy kangaroo that would kick and bounce around in a confined space, she needed no sedation because she couldn't move.

Dr. Harris arrived at the clinic early. He brought with him a full set of specialized tools, a surgical nurse, and another physician to assist during surgery. We were also joined by another veterinarian, an anesthesiologist from the nearest veterinary school two hours north, Louisiana State University School of Veterinary Medicine. Together we reviewed the X-rays and myelogram. Dr. Harris decided on a surgical approach through the back of Sally's neck.

About an hour later, the kangaroo lay on her stomach under anesthesia, ready for the surgery to begin. We placed her head on a rolled towel, allowing her neck to rest in a natural position. We clipped away a large patch of fur and scrubbed the area for surgery. With a scalpel, Dr. Harris made a vertical incision in the skin, starting just above the base of the neck. Next he used scissors and forceps to bluntly dissect between the muscles, tracing the path of each one to identify its function. Using tiny clawlike clamps, he pulled the muscle fibers off to one side as he slowly worked deeper. His goal was to get down to the affected bones without damaging the
muscles. This was a painstaking process, and the fact that nobody had ever done it before in a kangaroo made it slow going.

In terms of surgical anatomy, we had few bipedal mammals to use for comparison. Dr. Harris frequently asked us what was normal and what was not. He pointed to a place where one of the neck muscles split in two. Was that normal anatomy, or had it occurred when the kangaroo hit the fence? We really didn't know. No textbooks existed for the kangaroo spine.

Fortunately, many aspects of anatomy and surgery are universal among mammals. For example, both kangaroos and humans have cartilage lining the articular surfaces (facets) between the vertebral wings and cartilaginous discs between the vertebral bodies. Both have ligaments holding the vertebrae in alignment, tendons that attach bone to muscle, and muscles crossing the surfaces of multiple vertebrae to give the spinal column strength. And in any species, the rate of post-operative healing depends on the degree of tissue damage and the quality of the blood supply to the affected area.

With these principles in mind, Dr. Harris was diligent, careful, and delicate, extrapolating from his experience in humans to preserve the normal anatomy and blood supply while making his way down to the misaligned bones. After half an hour, the affected vertebrae had been exposed with minimal bleeding. That in itself was an amazing feat.

Then came the most difficult, risky part of the procedure: realigning the spinal canal. In pushing the vertebrae back into their original positions, we faced one of two outcomes. We could successfully align the spinal canal and remove the
pressure on the cord, allowing the damaged nerves a chance to heal. Or we could align the bones but in the process damage the cord further by increasing the trauma and bleeding in the area.

Carefully, and still ever so slowly, Dr. Harris pushed the vertebrae back into their original positions with his skillful hands. We heard a slight pop. Everyone held his or her breath except for the anesthetized Sally, who continued to breathe normally. A good sign, given that any manipulation of the spinal cord can disrupt descending signals from the brain. Nothing seemed to have worsened, so we continued the procedure.

After placing the spinal canal in what we hoped would be its normal position, Dr. Harris drilled small steel pins through the spinal processes of the second and third vertebrae. He wired the pins to each other and across the top, forming an H-shaped pattern. “It's known as a modified Dewar's technique,” he explained. The repair held both vertebrae firmly in place.

Next, we used bone cement to reinforce the pins and wire, knowing we couldn't ask the kangaroo to sit still and stay in bed for a couple of months. We considered a bone graft to add support, but rejected the idea for the same reason. She needed complete, or near-complete, stability the moment she woke up. Her first hop, no matter how soft, would send vibrations right up to the unstable area. A bone graft would take weeks to solidify. We questioned whether the bone cement, the kind used to secure a new hip joint in a human, would be strong enough in the long run, but it was our only option.

During the entire procedure, Dr. Harris had remained calm, methodical, and relaxed. Even during tense moments, his voice and manner remained steady. When he removed his mask after the surgery, he looked pleased as he surveyed his handiwork. I guessed that he saw the entire effort as fairly routine. He simply applied what he already knew to a different species. To me, it was nothing short of a small miracle.

Dr. Harris knelt down next to the kangaroo while she woke up from the anesthesia. Watching the two of them, I noticed a linear scar crossing the back of the neurosurgeon's neck. My mind came to an instant conclusion, confirmed months later when I finally got up the nerve to ask: the doctor had undergone a similar surgical procedure years earlier. Maybe that's why he'd become an expert in this field.

Sally lay on her side, shivering as the anesthetic wore off. It would be some time before we knew if the kangaroo could use her limbs. We'd taken radiographs at the end of the procedure and everything looked good—in perfect alignment. Nevertheless, we could not be certain she still had nerve function.

I saw the surgeon's clinical expression soften into a look of gentle, benevolent concern. It lasted only briefly—a few seconds—and then he smiled. From then on, I knew that Sally would be a patient our kind surgeon would never forget. He had felt what she felt.

Animals often represent more to us than their simple selves. Every patient deserves our empathy and compassion. Many also earn our respect, affection, or sympathy for a variety of reasons. We often try to control these emotions when they surface, as Dr. Harris did while working on Sally. Too much feeling can get in the way of good medicine. Too much
worry about what the animal is feeling can draw your attention away from the task at hand. Alternatively, too little makes it impossible to do your best.

Sally made a relatively rapid and complete recovery. It was not easy, but we kept her in a heavily bedded and padded recovery stall, much like the ones used for horses recovering from anesthesia. Four heavy pads covered the walls, preventing the animal from hurting herself if she stumbled trying to sit up or stand. The abundant straw bedding helped make the kangaroo comfortable. By the third day she had recovered movement in her legs and tone in her cloaca. Her appetite picked up and she accepted all of her food treats.

Over the following weeks, Sally became stronger and her movements gained coordination. We often looked in on her, only to find her looking curiously back at us while munching on a piece of hay. For her physical therapy, we helped her to her feet and held her tail while she hopped in place. After thirty days in our hospital, she could stand for several minutes at a time. After ninety days, she had completely recovered. We walked the kangaroo into a large plastic kennel and took her back to the exhibit.

For years afterward, I offered Dr. Harris an update every time I saw him. I'd describe how well the kangaroo was doing on exhibit. She appeared healthy and active, indistinguishable from the others. Dr. Harris would smile broadly and say, “Of course she's fantastic. She's Sally!”

Our neurosurgeon, a physician and scientist, took a great leap in this case. He allowed himself to identify with a kangaroo. I'd like to see that kind of emotional crossover into the animal kingdom happen more often.

Born and raised in Mexico City, Mexico, Roberto F. Aguilar graduated from the National Autonomous University of Mexico in 1987. He did an internship in veterinary medicine at Oklahoma State University and a clinical residency in orthopedic avian surgery at the University of Minnesota. He served as staff veterinarian and then senior veterinarian at the Audubon Zoo in New Orleans from 1992 to 2005 and is currently director of conservation and science at the Phoenix Zoo. The author of numerous publications, including a book on exotic animal medicine, Dr. Aguilar has lectured extensively in most of Latin America and is the manager for Latinvets, a Listserv with more than 600 members in Latin America, Europe, and the United States.

I WAS PREPARING
for the day's cases when I heard over the radio, “Any 500 veterinary unit, 10-76 polar bear dens
stat
!” At Chicago's Brookfield Zoo, our vet hospital call number is 500. The urgent message directed that any and all zoo vets go straight (called 10-76) to the polar bear grottoes. Since I was the only one working that day, that meant me.

Running out the door, I called to our two vet students to follow. This would be a learning experience for them, no matter what the problem was. We sped across the park to assess the situation. The polar bear keepers met me at the entrance to the dens and took me to see Aussie, down a long, cavelike, cement-floored corridor to the inside holding dens. Despite the rising summer heat outside, the cool, moist air carried the unmistakable smell of bear—a strong musty
odor. Aussie, our twenty-year-old male breeding polar bear, stood at the cage front. He had a very large swelling, about half the size of a basketball, protruding from his belly button.

I bent down to look at him through thick iron bars, so that the big polar bear and I were face-to-face. He was obviously in extreme discomfort, legs splayed, swaying back and forth with the biggest hernia I had ever seen. Aussie needed emergency surgery.

I'd repaired hernias before, but never in such a large patient. The students searched the literature about hernia repair in bears, finding very little. I spoke to a vet at another zoo who'd done a similar—and successful—surgery on their polar bear. It helped to know that we wouldn't be the first to attempt this procedure and that we could use a standard domestic-animal surgical approach. Moving Aussie to and from the operating room presented the biggest challenge.

I decided to call the vet school for help. Unlike zoo vets, veterinary surgeons operate daily and repair hernias often. They don't work on bears, of course, but this was not a bear-specific problem. Any species can develop a hernia. I'd anesthetize Aussie by dart, we'd move him to the hospital clinic for the surgery, and the experts would take it from there. They'd extrapolate using techniques established for domestic animals. The operation would go faster, and I'd be able to focus my attention on the logistics of working on a polar bear.

Four hours later, we were ready to start. A veterinary surgeon and an anesthesiologist from the University of Illinois at Urbana-Champaign College of Veterinary Medicine were on their way. Our vet techs had prepped the large-animal surgery room for a thousand-pound patient. The chief of
police had organized an escort; the zoo's forklift driver was on his way. A crowd of keepers, assistant curators, and curators had gathered to help.

Earlier, I'd contemplated the best choice of anesthetic agents for this older, compromised polar bear. Patient safety, the safety of all the staff who would be helping to carry the bear, and the safety of the visitors in the park were all of equal concern. Polar bears are extremely dangerous animals, smart and quick, one of nature's most powerful carnivores. If I miscalculated the amount of drug needed and Aussie woke up from his anesthesia during transport across the zoo grounds on a busy summer day, we would have a serious problem. There isn't an anesthetic dart that would work fast enough. In that case, our zoo police force had the authority to shoot to kill our patient.