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Species-Spanning Medicine

“By providing that data point, it’s almost a legacy for their own dog,” Breen says. “Every dog we recruit, we ask the owner for a picture to put on our wall of honor. We have hundreds and hundreds of pictures of dogs. It helps ground people in the lab, and makes them realize what they’re dealing with is not just a piece of tissue but somebody’s beloved companion that needs to be treated with the same kind of respect.”

Under microscopes, Breen studies chromosomal changes within cancer cells, changes that have been shown to duplicate those that occur in humans. “If we look at what overlaps, it’s those shared genes that highlight the major drivers in the cancer process,” he says.

The aberration of particular chromosomes allows Breen to identify which therapies will offer maximum survival chances. In lymphoma cases, up to 90 percent of dogs respond to chemotherapy and go into remission, but only about half live longer than nine months. By looking at the genetic differences between the dogs who survive for short times and those who survive longer, Breen’s team has developed a test that determines how long a dog will stay in remission; this test will, it is hoped, eventually be available for use with humans.

Experts estimate that one in four dogs will develop cancer in their lifetime. About 50 percent of those over age 10 will die from it. The types, incidence and outcomes aren’t always identical to those in humans, but even in those differences, other clues and opportunities may be found.

Bone cancer, or osteosarcoma, for example, affects a whopping 60,000 dogs a year. In humans, there are only about 900 cases a year and, as a result, its research has never received the kind of funding awarded to work being done on more widespread cancers.

By looking at the disease itself, as opposed to its effect on a singular species, some less high-profile diseases (in humans) can get more attention, and progress can be made more quickly, Breen says.

“We ignore whether it’s in dogs or people, focus on the cancer and get to the biology faster.”

Down the road, such research might keep someone else from hearing those five fateful words Breen remembers hearing as a child, when his own Border Collie cross was stricken with cancer: “There’s nothing we can do.”

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Rudolph Virchow, though he wasn’t credited for it in his lifetime, is considered the father of “one medicine.” The 19th-century pathologist coined the term “zoonosis” and created the field of comparative pathology.

“Between animal and human medicine there is no dividing line—nor should there be,” he said. “The object is different but the experience obtained constitutes the basis of all medicine.”

Two centuries later, a variety of factors breathed new life into his old idea. Recently identified zoonotic diseases, like swine and avian flus and West Nile virus, became major public health concerns. At the same time, dissatisfaction was mounting with research studies involving mice, primarily because their findings often weren’t transferable to humans. There was a growing recognition that all animals, both wild and domestic, serve—like the canaries once used in British mines—as sentries for environmental hazards.

Dogs, while at the forefront of much modern research, also played a large role in reviving the species-spanning way of thinking. On top of the tremendous diagnostic and research value it held for dogs, the successful completion of the canine genome map in 2005 showed how similar dog genes are to our own. It also reinforced how much more quickly canine health research can progress. Mapping the sequence of the canine genome cost about $50 million and took one year, while mapping the humane genome cost more than $3 billion over 15 years.

It was one year after that benchmark, in 2006, that the American Medical Association and the American Veterinary Medical Association issued a joint declaration encouraging more partnerships and information sharing between the two branches of medicine.

For far too long, doctors of human medicine and doctors of veterinary medicine—and researchers in the two fields—operated on separate planes. By coming together and sharing their findings, proponents of one medicine held, new opportunities could be realized and new cures, possibly, found.

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