The Rhino with Glue-On Shoes (17 page)

Reaching the back of the plane, I stopped to check on Echo and Wee Tee, resting peacefully, seemingly unfazed by the events of the day. With a flashlight, I peered down their blowholes to study the color and pattern of their mucous membranes, the characteristics of their eyes, individual markings—anything that might help me to be a better doctor to them. It would take years for me to develop the kind of relationship I'd seen in Florida between Tessie and the park staff, but this was a start.

As we landed, the water shifted in the dolphin carriers. Miraculously, not a drop spilled. We gathered up our equipment, readied our packs, and stretched our stiff bodies. When the airplane cargo door glided open, the interior lights also went on. I squinted in the harsh gleam, trying to adjust to the fact that we'd actually arrived. Into the plane stepped members of the Department of Agriculture, along with the president of Atlantis resort. We excitedly introduced them to our precious cargo.

I poked my head out the doorway and saw that a crowd of more than 150 people had come to welcome the dolphins at this predawn hour. The warm, moist air felt soft and comforting on my tired face. One by one, the dolphins were loaded off the plane to applause and expressions of joy. A forklift loaded the transportation units onto four flatbed trucks. As the sun rose, we went rolling down the streets of Nassau. Although it was now a busy time of morning in town, the military escorts provided by the city carried out their job perfectly. We seemed to reach our destination in no time. These sixteen new residents were obviously very special to the Bahamians!

When we came to a stop outside the dolphins' new home, a crane appeared and gently lifted the hammocks from the transportation units. The dolphins were carried by teams of ten people down to their new open-air holding pools, filled with beautiful blue Caribbean water. Each animal was set gently along the edge of the dock, with the pectoral fin nearest the water tucked beside its body. Someone called, “One . . . two . . . three . . . GO!” and the dolphins were carefully rolled out of the hammocks and into the water.

The dolphins' response amazed me. I'd seen these animals swimming quietly or simply resting in their various temporary homes. Here, they immediately began leaping in and out of the water, occasionally chasing small fish, rolling over one another in play. Never had I seen them so active!

I smiled with a sense of accomplishment as I sat on the dock and watched the dolphins convene. The adrenaline that had been coursing through my body was waning and the effects of being awake for thirty-six hours were beginning to take their toll. “Welcome to your new home, beautiful dolphins,” I said.

IV

P
UZZLES AND
M
YSTERIES

Despite their years of special training, zoo vets are acutely aware of what they don't know. Most of us keep a library of textbooks and subscribe to reference material on the Internet on topics ranging from domestic and wild animal medicine to emerging infectious diseases and human pediatrics. We also publish what we learn from clinical practice and applied research, adding to the growing annals of zoological animal medicine. When strange cases arise, as they often do, we call our colleagues and other experts for ideas.

Solving medical problems in any species is analogous to putting together a difficult puzzle without all the pieces. Though the reference literature grows by the year, zoo vets confronted by a mystery often must rely on hunches backed up by personal experience, ingenuity, and patience.

The animal's clinical signs are important clues. Some injuries are obvious, like a bleeding wound or broken leg. But trauma to muscles or internal organs may not be evident from a distance, or even in the animal's overall behavior. And nervous animals can often override pain. An anxious impala may run on a sore foot as if nothing were wrong. Signs of illness can be equally obscure. A wolf with a liver problem and a history of vomiting may keep its food down at one meal, but not the next. Sometimes it's what an animal doesn't do that gives cause for worry. A chimpanzee known for his feisty behavior is not feeling 100 percent if he misses an opportunity to spit a mouthful of water at the vet.

As the basis for interpreting an animal's behavior as abnormal, zoo vets also need to know the biology of the species concerned. The animal's natural history—its preferred habitat and diet, its reproductive cycle—influences how well it takes medicine or tolerates anesthesia and hospitalization. Certain species, especially nervous or social ones like birds, hoofed animals, and primates, can develop entirely new problems associated with the stress of treatment.

Once we've done a hands-on physical exam and run various laboratory tests, we check our results against previously established baseline data for that species. Sometimes that information may turn out not to be very useful. For example, published normal results for a complete blood count, or CBC, in a golden monkey might be based on a handful of animals, some living in captivity, others free-living. With such a small sample size, it's impossible to distinguish subtle differences between the results for individuals of different ages and sex. Some variation may be entirely normal. By contrast, baseline data for these tests in humans and domestic animals is widely available and based on huge sample sizes.

With the data gathered, we try to put the pieces of the puzzle together. We can usually pinpoint the problem to a particular body system. As in any species, there are only so many: cardiac, respiratory, digestive, nervous, immune, reproductive, urinary, and musculoskeletal. But certain diseases, like cancer and nutritional imbalances, affect the whole animal.

Like all doctors, zoo vets prefer to base their therapy on a specific diagnosis. But while tests are pending, our patient may be suffering. If we think we can help the animal feel better, without doing harm, we will prescribe nonspecific treatment, or perhaps treat for the most likely problem. The patient's response to therapy often helps us to confirm or refute our best-guess diagnosis. Sometimes the definitive test result comes in long after the animal has healed.

But as the stories in this section show, some puzzles elude solution—at least in the beginning. Others are solved in time to save the patient. And some, to our great frustration, remain unsolved. The patients here include a Bengal tiger, a giant Pacific octopus, a white rhino, a group of dung beetles, a red-ruffed lemur, and a Pacific bottlenose dolphin.

Lucy H. Spelman, DVM

The Limping Tiger

by David Taylor, BVMS

Z
elda, the Bengal tigress at Windsor Safari Park in the UK, was not displaying much fearful symmetry. She padded unsteadily across the green sward of the reserve where she and twelve of her fellow tigers lived. I stood next to Ginger, the highly experienced ex–circus man in charge of the park's big-cat collection.

“It beats me,” he said. “Fit as a fiddle two days ago. Look at her now! I put her in a small cage this morning and checked her legs. Nothing amiss that I could see. No bite wounds, no overgrown claws pricking her foot pads.” He shook his head slowly. Zelda was Ginger's particular favorite. He had helped me deliver her when her mother had difficulty giving birth six years earlier, in 1982.

“Let's get her inside,” I replied. “We'll have a proper look at her under anesthesia.”

By gently guiding her with a Land Rover, Ginger and his men persuaded Zelda to go into her night-house. I used my dart pistol to inject her with a light dose of ketamine, a short-acting anesthetic.

Five minutes after the flying dart hit her rump, she was asleep. We could safely enter her quarters. Ginger unlocked the door and I went in. (I have always made a point of being the first to enter when a potentially dangerous beast has been sedated. Since the vet picks the drug and the dose, he or she should take responsibility for the initial close encounter with the animal—just in case it isn't drowsing quite as deeply as it might appear.)

I knelt beside this most magnificent of cats as she lay on her side, resting on a bed of wooden railroad ties covered with a layer of straw. I checked her heart and lungs with my stethoscope and took her pulse by feeling beneath her upper-most hind leg for the femoral artery. All fine. I reckoned I had about ten minutes before she began to rouse significantly. I ran my fingers over her limbs. I could find nothing wrong with her great paws, nor were there any abnormal swellings along the long bones of her legs. One by one, I felt her joints, moving and gently pinching them. Was their movement smooth? Could I feel any loss of fluidity, any “scrunching” sensation of bone rubbing against bone? Were the ones on her right side the same size and shape as those on her left?

I soon felt something. One—nay, both—of her knee joints were puffier than normal. Then I got the impression that one hock (ankle) joint and both the carpal (wrist) joints of her forelegs were enlarged. I could feel extra fluid under pressure between the adjoining bones.

“What do you think, Doc?” whispered Ginger, kneeling beside me.

“Joints for sure,” I replied, “but what exactly I don't know. Could be arthritis, perhaps caused by a bacterial infection. Never seen anything quite like it in big cats before.”

On occasion, I had dealt with cases of multiple joint inflammation, or polyarthritis, in other species. We had a case in a giraffe, also at Windsor, that we ended up treating with acupuncture. But I had never heard of it in big cats in zoos or circuses. I decided to give Zelda a course of antibiotics together with anti-inflammatory corticosteroid drugs. We gave this to her by injection and planned to continue dosing her in her food.

“I'll come back to see her again in five days.”

The telephone rang early next morning. It was Ginger reporting that Zelda's condition had worsened markedly. She could barely walk and was unable to leave the night-house. I set off at once for the safari park. As I drove, I puzzled over the tigress's condition. She wasn't old, so age-related osteoarthritis seemed unlikely. Could it be septic arthritis caused by bacteria arriving via the bloodstream? Possible, but I'd never seen or heard of such a condition in big cats. What to do? Radiography perhaps. Draw off a sample of what might well be purulent joint fluid for bacteriological culture? Probably the best course. Treatment? For the moment at least continue antibiotics, switch from corticosteroids to nonsteroidal anti-inflammatory drugs until I had a precise diagnosis. Certainly, I had to relieve Zelda's pain as a priority.

Ginger was waiting by the tiger area gate when I arrived. “She's bad, Doc,” he said as we walked to the night-houses. “An' on top of her lameness, her appetite's gone and bless me if her eyes aren't changing color!”

“What do you mean?” I asked, eyebrows raised.

“The shine has gone; they're dark-colored now.” He muttered an oath under his breath.

The tigress lay awkwardly on her bedding. The swollen joints were now plain to see and, yes, her eyes did appear to have changed color. I immediately set about preparing a flying dart and filling it with ketamine. The cat managed a growl of protest when the dart hit her.

As soon as she was drowsing peacefully, I began by inspecting her head with the apparently color-changed eyes. Looking closely, I confirmed what Ginger had described. Her eyes were indeed darker. The effect was caused by an accumulation of dark blood in the anterior chamber, between the front of the iris and the back of the cornea, of each eye. This was something I had never seen before in any species of cat—hyphema, bleeding within the eye.

Next, I turned to the puffy joints. After shaving and disinfecting a small area of skin over one hock, I passed a sterile hypodermic needle into the enlarged joint cavity and attached a syringe. Pulling back the plunger, I waited for fluid to emerge. Straightaway it did. Within a couple of seconds, I had a syringe full of pure blood. Oh Lord, I thought, blood in the eyes, blood in the joints, blood perhaps leaking elsewhere in the body. I think I know what this might be.

Ginger saw the worried expression on my face. A small tear glistened on his cheek. This burly, chain-smoking, beer-loving, three-fry-ups-a-day head keeper—who knew more about the ways of big cats than any other animal man I had ever worked with—understood Zelda was in trouble.

“T'aint serious, is it, Doc?” he murmured. “Arthritis can't kill, can it?”

“I'm afraid it
is
serious, Ginger,” I replied. “If I'm right, Zelda has been poisoned.”

There was a long pause before my companion spoke again. “Poisoned? By what? How? Who by?”

“A chemical that stops blood clotting. The most likely culprit is the rodent poison coumarin, better known as warfarin. Kills rats and mice by causing them to hemorrhage internally. Sometimes happens in domestic animals that eat rat poison, though I've never seen it in exotic cats. Are you using warfarin to control pests in the reserve?” I knew that the stuff was sometimes used in zoos to get rid of rodents.

“Warfarin. Yes, it's used by the pest control firm that the park contracts, but it's never put down in bait boxes inside the reserves, only outside where our animals couldn't get at it.”

“Do you ever see rats in the reserves?”

“Occasionally. I've seen tigers, lions, and cheetahs sometimes chasing one.”

“And catching and eating it?”

Ginger thought for a moment and then said, “I have seen it happen.”

I decided to take a blood sample from Zelda while she still slept and send it to the local laboratory. The key test I wanted to run was called a prothrombin time, a measure of blood coagulation time. My problem now was that although I knew what a normal prothrombin time should be for humans and domestic cats (both the same, between eleven and fourteen seconds), I had no idea what it should be for tigers.

“Let's drive round the reserve and see if all the other cats seem okay. I'll also knock out Zeinab, Zelda's mother, so I can take a blood sample from her for comparison.” As we left Zelda's night-house I saw her pass a little urine; it was the color of rosé wine.

All of the other tigers seemed perfectly healthy. Using my telescopic dart rifle, I injected Zeinab's shoulder and within a few minutes had the necessary blood. While the two samples were sent to the lab, I called the big-cat keepers together and explained what I thought had happened.

“An animal doesn't have to eat warfarin itself to be poisoned. It can also happen if it eats an animal that already is suffering or dead from consuming warfarin. Usually for poisoning to happen, the warfarin has to be ingested on several occasions, but some species can be affected after a single dose. We just don't know how sensitive tigers are. Have any of you guys seen rats inside the tiger reserve?” I asked.

Several of the men nodded at once.

One keeper said, “Actually I saw Zelda chasing a rat, killing it, and eating it a few days ago. She didn't have to make much of an effort. It was walking slowly and staggering a bit across some short grass.”

Here was a highly plausible explanation for how Zelda became sickened by warfarin. A rat eats the poison bait outside the tiger reserve, falls ill, and, when close to death, goes blindly through the chain-link fence and wobbles its way into the jaws of the tigress.

Within an hour, the laboratory rang. Zelda's prothrombin time was fifty-five seconds; her mother's blood coagulated normally in twelve seconds. I was now certain that the tigress was poisoned by warfarin.

Warfarin achieves its toxic effect by attacking vitamin K, an essential component of the blood-clotting mechanism. Treatment for Zelda meant big doses of vitamin K for the next few days at least. We put an urgent call to the pharmaceutical wholesalers for a courier to be sent to the park at once, bringing more vitamin K injectable solution than I'd ever used in my whole career.

By this time, Zelda had come round from the anesthetic, so I gave her the first dose by flying dart from a blowpipe. Later that day I repeated the procedure.

Within twenty-four hours, there was a noticeable improvement in the tigress. She could rise to her feet and walk with less difficulty. Twice a day for the next week, I gave her more vitamin K by blow dart. By the third day, her eyes were back to their usual appearance of burnished gold. The blood in the anterior chamber gradually reabsorbed. The color of her urine also returned to normal, clear yellow, and so did her appetite.

Ten days later, the joint swellings had fully resolved and Zelda could walk, run, and spring with her usual elegant fluidity. Another prothrombin test gave us a gratifying reading of fifteen.

Ginger and I went to the pub in Windsor to celebrate Zelda's recovery. Warfarin would no longer be used by the rodent controllers at the safari park, he informed me. I announced that I'd be presenting the park with a pair of Lancashire heelers, the best little ratting dogs I'd ever come across.

Soon the dogs joined the safari park staff and began patrolling the grounds with the security men during the night. Rats were never much of a problem in Windsor Safari Park from then on. Zelda herself went on to have several litters of fine cubs.

Sadly, the safari park closed several years later. I bumped into Ginger while walking through Windsor. We talked about his tigers, which had been relocated to parks in the English Midlands.

“Went to see old Zelda a couple of weeks ago,” he told me. “She's in fine fettle. But I'll tell you what, Doc, we should all keep away from hospitals. These physicians are a dangerous lot! My pal's had heart trouble and the quacks wanted to put him on warfarin—same stuff as poisoned Zelda!”

I reassured my friend that the infamous rat poison was nowadays being used as a lifesaving anticoagulant in the blood of human patients. Ginger looked doubtful. On that note, we adjourned to the pub.