Originally published in the Winter 2007 Lincoln Park Zoo magazine

When doctors prescribe medications they can’t be sure patients will follow the usage guidelines once they leave their office. When zoo veterinarians prescribe medications to the animals, however, keepers and veterinary technicians are responsible for ensuring that each pill gets swallowed, each ounce of cream is applied and each injection is delivered.

Of course, getting a penguin to swallow pills, a snake to hold still while ointment is rubbed on its skin or a gorilla to accept an injection is no easy task. And administration of the drugs is actually the easy part of the equation for Lincoln Park Zoo veterinarians Kathryn Gamble, D.V.M., and Claude Lacasse, D.V.M. Figuring out which drugs to use—and how much of each—is the first and most difficult step when medicating ailing animals.

“We have to study size and species differences when determining dosages,” says Gamble, director of Veterinary Services. “For example, black rhinos have a similar physiology to horses, for which we know dosages for many drugs. So it may be just an increased dosage for the rhino’s larger size. But when you have a sick aardvark, where no domestic-animal model is available, you’re exploring uncharted territory.”

Knowledge Base
It’s a good thing the explorers are so knowledgeable. Gamble has a Masters of Science degree in veterinary pharmacology, studying pharmacokinetics in African antelope for her thesis project. She has continued such research projects at the zoo as well as mentoring Lacasse, who received her doctorate in veterinary medicine from the University of Montreal and completed internships at the school’s Raptor Center and Birmingham Zoo before joining Lincoln Park Zoo in 2002.

Pharmacokinetics is a mathematical translation of the way an animal’s body affects an administered drug. “I think this process is exciting, ” says Gamble. “It is a way to expand information that we have about domestic animals to exotic species.”

Much more is known about treating domestic animals than exotic ones. (Humans have been managing livestock much longer than they’ve been managing lions, after all.) But there are resources available to the veterinarians when an illness must be researched.

A message board supported by members of the American Association of Zoo Veterinarians contains data on everything from arthritic antelope to wheezing zebras. Textbooks and manuals, like the “Veterinarian Drug Reference,” line the walls of Gamble and Lacasse’s offices at the C.H. “Doc” Searle, M.D. Animal Hospital. And Gamble and Lacasse bring with them years of education and daily practice with crocodiles, cockroaches and countless other critters.

“Each time we learn about pharmacokinetics in a given species, we build for the next problem,” explains Lacasse.

Common Treatments for Common Ailments
The veterinarians estimate that, over a year’s time, 15–20 percent of zoo animals receive some form of medication. “In any population, like a city, there is going to be a percentage of people who are sick,” states Gamble. “A zoo is no different in that animals need treatment.”

Osteoarthritis is one of the more common problems that Gamble and Lacasse combat at Lincoln Park Zoo. It’s a problem that affects all zoos for a simple reason—captive animals, with ample food, proper healthcare and a lack of predators, live longer than wild animals. As such they experience problems with aging that most wild animals simply don’t experience.

Species-by-Species Challenges
There is a philosophy among zoo veterinarians: A cat is not a small dog. A dog is not a small human. It’s a pithy way of highlighting the fact that each species—no matter how similar or dissimilar—requires its own medical approach.

Lacasse cites the example of red-tailed hawks that require treatment for joint inflammation. Although a study had been conducted on parrots that provided guidelines for using meloxicam (an anti-inflammatory), hawks are not parrots and cannot be handled as frequently. It was determined by pharmacokinetics that hawks eliminate the meloxicam so rapidly that they would require eight daily doses, which was impossible and counterproductive. Lacasse instead treated the hawks with flunixin meglumine which needed to be administered only once a day.

When species as similar as parrots and hawks require such different approaches, it is not surprising that even more disparate species pose greater challenges. Ruminants like Bactrian camels digest huge quantities of grass over long periods of time, meaning that swallowed medicine can get lost in the large volume of the stomach. Allen’s swamp monkeys, which store food in pouches in their mouths, can hide pills and discard them when keepers are out of sight.

In cases like these, Gamble and Lacasse employ strategy or downright sneakiness in the best interest of the animal. The camels receive powder shaken atop wet grain, while the monkeys receive medicine squirted into fruit.

The black rhinos can be given antibiotic powder mixed into Jell-O cubes or pills studded like cloves into an apple. Liquid medicine is injected into worms that are then fed to sick hedgehogs. And small fish fed to penguins, which are gulped in one bite, can be loaded with pills. “We love it when animals swallow food whole,” beams Lacasse.

Sometimes manufacturers make the process of administering their goods easier, producing medications in different forms (from pills to pastes to powders) and many flavors. The antibiotic metronidazole, which naturally has a bitter taste, comes in a banana flavor that most animals will tolerate. Medicating animals requires a blend of science and savvy.

Gamble and Lacasse are graced with both. From researching the right pharmaceuticals, to calculating the proper dosages, to determining how to best administer the product to the animal, zoo veterinarians employ their knowledge of science, a history of hands-on experience and, in some cases, that proverbial spoonful of sugar to help the medicine go down.