Grad studies stress responses in grizzlies and polar bears
By Joel Deshaye
For a researcher whose job sometimes entails chasing polar bears or grizzly bears by helicopter, Marc Cattet is careful to explain that the glamor of the job is superficial.
Cattet is a recently graduated veterinary pathologist at the U of S who specializes in bear biochemistry and bear handling. For Cattet, the helicopter chase is an unfortunate necessity.
"I still get a big thrill getting into the helicopter and its a great way to see the world," says Cattet, who has traveled the Arctic by air to get blood samples from polar bears. "And its really neat to see the animals from that perspective. But the reality is that theres a particular animal that youre going to dart. Its really stressful for the animal ... You can imagine yourself in that situation. And they dont know what a helicopter is. Thats not a pleasant part of the job ... Its always a big relief when youre leaving and you see the animal get up, and its an even bigger relief when a few weeks later you encounter that animal again."
Cattet collects blood samples from polar bears to understand their physiology, which has adapted to tolerate the stress of food deprivation in the Arctic. A polar bears metabolism allows it to survive long periods of fasting followed by high-fat feeding when food is available.
Relative to humans, polar bears are "insulin-resistant-C" a condition that has prompted comparison between bears and diabetic humans. The bears do not develop diabetes, however. Cattet says it is premature to hope that the study of bears will help cure a human disease; rather, his approach emphasizes the bears well-being.
With the health and safety of bears in mind, Cattet and Nigel Caulkett, an anesthesiologist at the veterinary college on campus, have developed an anesthetic drug that is reversible by an antagonist drug and that has effective painkilling properties for the bear. The current drug most commonly used to immobilize bears, Telazol, wears off slowly and does not effectively stop the pain caused by procedures such as tooth extractions which allow the researcher to determine the age of the bear by counting the tooths tree-like rings.
Cattet also works with a large-scale conservation project called the Foothills Model Forest Grizzly Bear Research Project, based at Hinton, Alta. He was hired in 1999 as the project veterinarian, whose job is to oversee the safety and the health of captured animals. He has also used this position as an opportunity to further test the newer anesthetic drugs for use on free-range bears.
"The animals are different in that setting," he says, comparing wild bears to the domesticated ones in zoos. "There are a lot more opportunities for adrenaline [a stress response] to manifest itself and override the effects of the anesthetic drug."
The study of the grizzly bear is important because, as omnivorous animals at the top of the food chain, they are "an indicator of ecosystem health." If the grizzlies are sick or in distress, it is likely that other animals in the ecosystem are experiencing increased stress.
Cattet and a team of co-investigators have recently proposed a research program to the U. S. National Science Foundation to examine grizzly bears "stress and health and how it ties in with population dynamics, human activity, and landscape change."
In Cattets research on polar bears and grizzly bears, the recurring question is about how bears respond to stress. "In the case of the polar bears, there was a stressor, and the stressor was food deprivation ... This is a stressor that polar bears have evolved and adapted to. With grizzly bears ... the stressor is human activity (industry, recreation, etc.) and the feeling is that this could be a stress that these animals cant adapt to."
Cattet explains that there is a point when stress irreversibly injures an animal. "Stress is a normal response. But there is a point when the duration and severity of stress gets higher and higher and longer and longer and the stress response basically sucks up the resources from other biological functions. And generally at that point it becomes distress. The response becomes non-adaptive."
Much of Cattets current work is with the Canadian Co-operative Wildlife Health Centre, whose mandate is to integrate broad aspects of veterinary medical science with wildlife management and wildlife conservation in Canada.
"Stress is a health issue," Cattet says. "Given that these animals are going to be handled, how can we reduce stress? The bottom line is that capturing animals is another form of exploitation. There are arguments for it and arguments against it. But its going to be done regardless. If there are ways of doing it better and safer, lets investigate and lets do it."
Joel Deshaye writes profiles of U of S graduate students as part of a fellowship with the College of Graduate Studies and Research.