Finding health in man's best friend
Finding health in man's best friend

STILLWATER — Veterinarian Michael Davis gets money from the military to research sled dogs' unparalleled endurance.

The National Institutes of Health pay veterinarian Dianne McFarlane to study aging in horses and toxicologist Carey Pope to examine how pesticides affect rats.

Researchers of human ailments increasingly are looking beyond laboratory mice to animals that are higher up the evolutionary ladder to figure out the causes of everything from cancer to aging.

Veterinarians have long played a role in public health, testing meat for dangerous bacteria and animals for viruses that can threaten humans, but they now are gaining importance in medical research.

Veterinarian-researchers at the Oklahoma State University Center for Veterinary Health Sciences are among those pioneering comparative medicine research.

Pope called organophosphate pesticides such as parathion "chemical cousins” of nerve agents such as those used in the 1995 sarin gas attack in Tokyo that killed 12 people. He wants to investigate whether the brain receptor that binds to the active ingredient in marijuana also can be used to mitigate the effects of nerve gas.

He thinks his approach has promise. He hopes the federal government agrees and will approve a research grant.

Animals, especially higher mammals, share many illnesses that afflict humans; understanding their processes may provide a bridge to understanding them in people.

McFarlane, a large-animal vet, worked on horses before embarking on a research career. She still works on horses, but in a different context now: She examines the roots of Cushing's disease, a disorder caused by abnormalities in the pituitary gland. Cushing's resembles Parkinson's disease in humans.

"My interest is really in the beginning of these diseases and in particular why the aging process puts you at more risk,” she said.

Researchers have studied aging in mice, but age-related illnesses are artificially induced. In horses, McFarlane can study aging as it happens naturally. Studying Parkinson's and other age-related conditions in humans is difficult, too; it's hard to catch people before treatment to observe diseases in their early stages.

"I think that there are some good (research) models from ‘companion animals' that are now being accepted,” she said.

McFarlane also studies aging in baboons.

Ebola. Rabies. AIDS. Infectious E. coli. All are thought to have come from animals.

"Rabies is the example everybody knows about,” she said, noting that 35,000 people worldwide die from rabies every year.

"Every day, practicing veterinarians protect human health. ... At any given vet school students will produce a T-shirt that says: ‘Real doctors work on any species.”'

Tests for heartworm in dogs can include tests for tick-borne diseases that sicken people.

Seventy-five percent of emerging diseases worldwide come from animals, said Little, a parasite expert who specializes in tick-borne illnesses such as Lyme disease, Rocky Mountain spotted fever and ehrlichiosis.

"Oklahoma is the place to be” to research tick-borne diseases, she said.

Little spoke recently at the Oklahoma School of Science and Mathematics, trying to entice students there to apply to the veterinary college's summer research program.

With the convergence of veterinary and human medicine, which she and others call the "one medicine” concept, study of disease, regardless of species, is the goal.

"My goal is to keep dogs and people healthy,” she said.

Veterinarians, she said, appreciate the diversity they must master to treat animals. For all their expertise, doctors treat only people.

"It's one of those obvious, in retrospect kind of things,” she said of vets in biomedical research, explaining that they "shine” when they collaborate with physicians who really understand human health in detail.

Vets provided a pet pharmaceutical company with data on disease prevalence in dogs. With the compilation, Little said, vets can analyze some diseases county-by-county.

"And that translates to a risk rate for humans,” she said.

Under other circumstances, dying animals can serve as "sentinels” to detect the presence of infectious agents. The introduction of West Nile virus into New York in 1999 is an example. Within four years, it had traveled to California.

"When people started reporting dead birds, they knew West Nile had arrived,” Little said.

"They're basically fatigue-proof,” he said, adding that the military would like to apply lessons from sled dog endurance to soldiers.

Davis first went to Alaska eight years ago to study exercise-induced asthma in sled dogs.

They proved a poor model for asthma study but a great model for other study.

"There was absolutely nothing known about the sled dog metabolism initially,” he explained. "We're at the point now where we have found some really compelling differences.”

Humans tire because their muscles run out of energy. Somehow, sled dogs are able to extract more energy from their blood.

Davis said animals have always been used in research — the important question is which animals to use.

"There's becoming a greater demand for domestic animals as sort of ‘translational tools,'” he said, describing how the National Cancer Institute is interested in cancer in dogs.

Moreover, he said, the Food and Drug Administration is becoming more reluctant to allow drug trials to proceed with people when based only on evidence collected from rodents — a traditional laboratory model.

"For our stuff, the sled dogs are absolutely unique,” he said. Alaska is unique as well. Instead of setting up a controlled environment to tire dogs, Davis simply waits at the finish line of races such as the 1,150-mile Iditarod.

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