Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
February 26, 1999
Researchers take shot at sheep disease
A vaccine developed by University of Guelph researchers that is administered via a biobullet could be the ammunition Rocky Mountain bighorn sheep need in the battle against a devastating disease.
Working with the Colorado Division of Wildlife, pathobiology professors Patricia Shewen and Ian Barker, along with graduate student Heather McNeil, developed a vaccine modeled after immunizations for shipping fever in cattle and pneumonia in domestic sheep.
They also tested three ways to give the vaccine to populations of wild bighorn sheep — biobullets, traditional injection and orally. Their research showed that biobullets, which dissolve in the body and contain a vaccine, may be the least-stressful way to immunize the wild sheep against pasteurella pneumonia. The pneumonia vaccine is encapsulated in a biobullet and shot from a gun at a distance. The animals only experience discomfort equivalent to an insect bite. This contrasts sharply with the traditional method of injection, which requires the wild animals to be penned, handled and given a needle. It also is more effective than oral methods.
The laboratory work for the study was completed at Guelph, and the Colorado Division of Wildlife, which is funding the research, administered the vaccine to the animals. North America is home to about 100,000 bighorn sheep, 7,000 of them in Colorado. Although the animals aren't considered rare or under threat of extinction, pasteurella pneumonia epidemics have been known to decimate herds, said Mike Miller of the Colorado Division of Wildlife. He's been studying respiratory problems in bighorn sheep for more than 10 years and has been looking for ways to control epidemics in a population. He notes that up to 10 per cent of Colorado's bighorns are affected by pasteurella pneumonia each year, and that anywhere from 10 to 70 per cent of a herd population can be lost through one outbreak.
The disease is spread through contact between populations and can also be transmitted between domestic sheep and wild bighorn sheep grazing the same areas. Once a herd has experienced an epidemic, it's difficult for the population to regain its strength, Miller said.
Although biobullets are not a new technology, using them to vaccinate bighorn sheep is a new application of the delivery method — a fact that has broad appeal for veterinarians and researchers interested in wildlife management, said Shewen, chair of the Department of Pathobiology. "If we find a method of delivery that is effective, easy to use and non-stressful, it could be applied to other vaccines."
Contact: Prof. Patricia Shewen, Department of Pathobiology, (519) 824-4120 Ext. 4453. For media questions, contact Communications and Public Affairs, Ext. 3338