The Hippo with Toothache (8 page)

In an odd sort of way, we were glad to see red. The blackened, unhealthy tissue wedged between his toes and into the cracks of his soles had outgrown its vascular supply. His back feet were the worst. We trimmed off the outside layers until we got down to healthy tissue, which bled profusely. I
watched the foot-trimming team for a minute or so, long enough to gauge how much more anesthesia time they needed. Then I turned my attention back to the rhino. Though we'd done this procedure many times before, it still felt like a big deal to put him under anesthesia.

At thirty-two, Mo was one of the oldest greater one-horned rhinos in captivity and genetically valuable. When he arrived at the National Zoo, in Washington, DC, in 1998, three years before, everyone hoped that he and Mechi, our female, would breed. He had never bred, and we knew he had a history of foot problems. Unfortunately, the pattern continued. Though the two seemed compatible, Mechi showed more interest in Mo than he did in her and his feet continued to deteriorate.

Fortunately, Mo handled anesthesia well. He'd stand still for the darting and slump to the ground ten minutes later when the drug took effect. Sometimes he'd go down in the middle of the enclosure, which made it easy. Other times he'd jam his great nose in a corner. We'd reposition him using a few ropes and about a dozen people. I'd put a catheter in his ear, start him on an IV filled with muscle relaxant, and then put a rubber hose up one nostril to deliver oxygen. The minute we had our first set of vital signs, the rest of the team got to work and the trimming began.

Given his age and the ever-present risk of complications, I tended to keep Mo's anesthesia on the light side. At the slightest indication of a problem, I could quickly reverse him (wake him up). Since this strategy meant that a loud noise or bright light could cause him to stir, we covered his eyes with a cloth drape, packed his ears with gauze, and kept a syringe full of anesthetic at the ready.

I lifted the rhino's blindfold and peered into his big dark
eyes. Even anesthetized animals have some sort of facial expression that offers a clue to their mental state. Mo stared past me, unblinking. His eyelids were stretched wide open, a side effect of the anesthetic, just as they should be at this stage in the procedure. I applied a bit more “eye goop,” a sterile ophthalmic ointment, to protect the surface of his corneas, and replaced the cover.

Checking for an ear twitch, I tickled the hairs in his upside ear. No reaction. Good. A chunk of brown wax stuck to my gloved finger. I fiddled with the hose delivering oxygen. No snort or change in breathing. Our monitors showed a steady heart rate and good blood oxygen saturation. I slipped my hands into his mouth to check his jaw tone; the muscles resisted. He'd definitely need a supplement of anesthetic before the team rolled him onto his other side. Otherwise, he might be able to kick out, or even try to get up. I also got a whiff of bad breath. Maybe we could float (file) his teeth if we had time.

“How's it going, Paul?” I asked. A large animal veterinarian, Dr. Paul Anikis had long since become a vital member of our zoo's consulting team. He'd driven ninety miles into the city from the Virginia countryside early this morning. It was now just past seven-thirty
AM
.

“These feet are a mess, Lucy, they really are. We're gonna try perfusing him today, the way we do in horses. The back feet, anyway. I don't think oral antibiotics will even touch this stuff.” Paul shook his head. “It seems like these toe pads are the problem. They've got to be really sore. If we can get a cephalosporin IV in there, it'll reduce all that swelling. We're mixing some up now.”

When Mo's feet needed trimming, the rhino's entire
demeanor changed. Normally, he never missed a chance for a food treat or a belly scratch. Erin, one of his keepers, had trained him to stand next to the bars of his indoor enclosure, close enough that she could reach in and work on his feet. While the other keepers distracted him with bits of sweet potato, Erin could give him a mini-pedicure.

But she could only trim bits of the overgrown tissue. Rhinos have three hooved toes on each foot. The skin between Mo's toes and the soles of his feet grew abnormally. At a certain point, this tissue fissured and cracked, allowing dirt and bacteria in and causing infection. Then it swelled. Mo couldn't stand without pinching this infected skin. It hurt. Because the problem affected all four feet, we didn't always see lameness, but his overall behavior changed. He avoided standing for long periods of time. Instead of enjoying his shower for an hour, for example, he would lie down in the middle of his enclosure. His eyelids and ears drooped. He would rarely come over to the bars. At that point, we'd schedule him for a complete trim under anesthesia.

I knelt back down next to the rhino's huge head, and watched again as Paul worked on the feet. He used a rope to fashion a tourniquet just below the rhino's tarsal-metatarsal (ankle) joint. Using a short piece of tubing with a needle on the end, a butterfly catheter, he quickly found a vein and injected the medicine. It would flood the tissue of the foot and stay there until he removed the rope. He followed that with some lidocaine, a local anesthetic, to ensure that Mo wouldn't feel anything.

For the bandage, Paul started with a combination of cotton and gauze wrap, covered by stretchy material called
Vetwrap. We'd been through a fair amount of trial and error with this last step. Our first set of bandages stayed on for only a few hours. Mo got his feet wet and kicked them off. We wanted the bandages to last a day or two, long enough to keep his feet clean immediately after the trim. The answer? Duct tape, of course: the wide gray sticky tape used to patch holes in just about anything. The brand in our kit that day had a clever brand name, Duck Tape, with a picture of a yellow duck standing in a puddle of water.

The team waited for me to give the rhino a bit more anesthetic and then pushed him up onto his sternum and over onto the other side, folding his legs under his body. Mo's heavy head rested in my lap during the shift, temporarily pinning me to the floor. Adjusting the blindfold, I checked his eyes again: no change. The extra dose had worked perfectly. I couldn't resist giving his neck a light pat. His rough skin felt like concrete with a little flex, reminding me of Rudyard Kipling's description: bumpy plates of armor.

Thirty minutes later, just as Paul finished bandaging the second rear foot, the rhino blinked and opened his eyelids extremely wide. The initial narcotic anesthetic had begun to wear off at just the right time. Minutes later, with most of the staff and equipment cleared away, I gave Mo a drug that would reverse the remaining effects of the anesthetic, took a last set of vital signs, and removed his catheter. Erin stayed with me at his head. Her shoes spattered with blood, she looked tired, having spent most of the time bent over, helping to hold Mo's feet.

“He'll feel so much better in a few days,” I said quietly as we waited for the effects of the reversal drug to kick in.

“I know,” Erin responded. “I just wish we didn't have to put him through this much, at his age.”

As the anesthetic reversal took effect, the rhino took a huge breath and lifted his nose. We pulled out the ear gauze, removed the blindfold, and backed out of the stall. Mo heaved himself to his feet, wobbling. Watery blood dripped from his elbows. He took a few steps, shaking his bandaged feet. The duct tape held. Once again, he'd sailed through the anesthesia. When I stopped by to check him two hours later, he appeared remarkably normal.

From past experience, we knew the rhino's feet would improve after the trim. We also knew we hadn't solved anything. The infection would return within several months. In fact, Mo had been suffering from this problem for much of his life. It started long before he came to Washington, DC, while he lived at a zoo in Florida. Maybe the antibiotic perfusion would knock down the bacteria and keep them away for a bit longer this time. Like Erin, I wondered how many more times we could anesthetize him safely.

Some months later, at a veterinary conference, I attended a presentation about foot problems in rhinos, expecting to hear the familiar advice: trim and trim again; try antibiotic footbaths. Instead, the speaker, Dr. Mark Atkinson, focused on what he had learned about greater one-horned rhinos in the wild. Throughout India, Nepal, Bhutan, and Thailand, this species—also known as the Indian rhino—lives in swampy grasslands and mud wallows.

Mark recommended that zoos dramatically change the way they housed these rhinos. A pool isn't enough, he said; give these animals the swamps and mud their feet need. Take
the pressure off their soles by getting them off gravel and cement floors. He also pointed out that many zoo rhinos were overweight, compounding the problem. Why weren't zoos providing the proper conditions? It was partly due to lack of understanding of what this species needs to be healthy, partly the cost of adding wallows, and partly the weather.

For nine months of the year in Washington, Mo had access to his outdoor pool and the mud around it. And he spent most of his time there. During winter, however, he lived mostly inside, protected from the cold. Mo's feet worsened within weeks of the start of wintertime housing routines.

While he spoke, Mark flashed images of normal feet from wild rhinos in Nepal alongside images of abnormal ones living in captivity. Rhinos have three toes and a main foot pad. They naturally bear most of their weight on their toenails, each analogous to a horse's hoof with a hard outer wall that extends well below a concave sole. Healthy wild rhinos are “toe walkers.” Since they naturally walk on soft ground, their toenails show very little wear. Captive rhinos have short nails with flat soles that fall even with the main foot pad; they are “pad walkers.”

Suddenly, Mo's real problem became crystal clear: his toenails were completely worn down from a lifetime on hard ground, exposing his soles—and then his main foot pad—to excess weight. Swampy ground might have prevented this problem, and it certainly had to be part of the long-term solution, but for now this rhino's feet were caught in a painful vicious cycle. Every time we cut the overgrown sole tissue back, it barely came even with his nails. He walked mostly on his sore soles.

I arranged for Paul to stop by to see Mo so I could show him some of the photos. He reacted to Mark's findings with a new idea.

“Okay, so let's put shoes on him,” he said.

“Shoes?” I was surprised. “Paul, you're crazy. How do we do that?”

“We'll just glue 'em on. No problem. I've been putting these aluminum shoes on the US Equestrian Team dressage horses because they're light, and you don't have to put nails through their feet to keep them on. We use epoxy and a fiberglass patch. You know, the way you fix broken turtle shells. If we can just get him up off his soles and give his nails some relief, they might have a chance to grow out more normally.”

“But won't we have to go back and take the shoes off at some point?” I asked, worried about the number of times we'd have to put the rhino (and ourselves) through anesthesia. The more I thought about an aluminum shoe glued onto the bottom of a rhino foot, the crazier it sounded. I imagined two scenarios: the rhino would wake up from anesthesia, tap around inside his enclosure, and throw off the shoes. Or the glue would hold them in place forever.

“Nah, he'll wear 'em off eventually. Most people probably won't even notice he has them on.” Paul thought for a moment. “Send me measurements of his back feet—the really bad ones—and some tracings of his footprints, if the keepers can get them. I'll make a prefab set of shoes so the whole thing goes quickly. I think we should do this sooner rather than later, before his feet get really bad again.”

We were all excited when the time came to give Mo his
new shoes. Once again, there was extensive secondary infection in his rear feet, though the front feet were not so bad. After the trimming and antibiotic perfusion, Paul pulled the shoes out of his bag. I'd visualized thick pads of some sort. Instead, they looked a lot like standard horseshoes, without the holes, and shaped a bit differently. Of course, the other difference was that Mo would wear three shoes on each back foot, one for each of his three toes.

Paul started prepping the shoes for the epoxy. He checked each one for size and shape. The shoe for the middle toes was a larger C shape than those for the smaller inner and outer toes. Since rhino toes spread out when the animal stands, the three shoes would support a fair amount of Mo's weight; his main foot pad would support the rest. The combined surface of the shoes would function as surrogate toenails.

Working at his usual rapid pace, Paul applied a thin layer of glue to the underside of each shoe. The bitter smell of adhesive filled the air. He pressed the shoe onto the sole close to the edge of the toe, and covered it with Kevlar fiberglass strips slathered in more glue. This patch acted like a Band-Aid to create a better seal and extend the life of the shoe.

Paul pressed the shoes in place for several minutes, allowing the adhesive to take hold, and then wrapped the foot lightly: no need for the heavy gray tape today. We wanted Mo to shed these bandages by nightfall so he'd be walking on his new shoes. As Paul finished side two, I said, “Hey, wow, snazzy shoes! Bet this is a first for a greater one-horned rhino.”

“Yup. I'm happy with them. He should feel a lot better. Let's see how he wakes up.”

Later in the morning, I came back to check on Mo. He stood drowsily eating hay. Erin smiled at him. Good old Mo—another uneventful recovery.

His bandages already off, Mo walked over to us, his feet making a light tapping sound on the concrete floor. He pushed his great one-horned nose between the bars for a piece of carrot. The eye ointment from the procedure had seeped into the skin around his eyes, making them look even rounder and darker than usual. Mo seemed exceptionally calm and relaxed, and we thought the shoes were already giving him some relief. Erin joked that he might start tap-dancing at any moment.