December 7, 2004

Researchers Study Cattle Altitude Sickness

LARAMIE, Wyo. (AP) -- Two University of Wyoming researchers are working on developing a test to diagnose altitude sickness in cattle. Cattle under a year old are especially susceptible to altitude sickness above 5,000 feet. But the condition, called brisket, can only be diagnosed by inserting a probe into the jugular vein and measuring blood pressure in the heart and lung.

Mark Stayton, associate professor in the College of Agriculture's Department of Molecular Biology, and Rich McCormick, of the Department of Animal Science, hope to come up with a simpler procedure.

They are working with Tim Holt, a veterinarian and faculty member at Colorado State University who has studied altitude sickness in cattle for more than 24 years.

"It can mean the difference between profit and loss in some operations," Stayton said.

A predictive test could help ranchers prevent the fatal sickness, and could have implications for human illnesses.

"In brisket these animals are starved for oxygen because it's difficult for them to force blood through their lungs," Stayton said. "In certain human diseases patients are also desperate for oxygen. If an artery is completely blocked, they have a heart attack.

"What we learn about it in humans can apply to cattle and vice versa," he adds. "Many genes are similar among vertebrates. That allows us to extrapolate from one species to another."

Above 5,000 feet, the reduced oxygen pressure causes the blood vessels in the lungs of certain cattle to constrict, requiring the heart to work harder to push the blood.

The heart muscle enlarges to compensate but may stretch so much that the valves inside do not meet as they should, thus producing a backflow of blood with each contraction. The heart has to push even more, it continues to balloon, and the problem becomes more severe.

Meanwhile, that increases blood pressure, causing a leaking of fluids, according to the researchers.

Livestock stricken with brisket tend to have swelling in the neck and chest due to fluid accumulation in those areas. The cattle also experience depression, weakness, diarrhea and eventually heart failure.

The only way to cure the problem is to move the cattle out of high-altitude areas. "However, if brisket disease syndrome has damaged the heart and lungs, then even a lower elevation will not reverse its effects," McCormick said.

Aside from the heart and lung probe, it is impossible to determine at lower elevations which cattle are susceptible to brisket.

"What we are shooting for is a more affordable rapid diagnostic kit that is less burdensome and that can be used by the ranchers themselves," McCormick said. "Not everyone can do heart catheterizations on cattle and interpret the results."

The researchers hope to come up with a way to draw blood from cattle and analyze their DNA to determine susceptibility to brisket.

"What we are looking for are genes that are altered in an animal that has brisket disease. We need a fingerprint," Stayton said. "Once we have identified those genes, we can invent a field diagnostic test."


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