Bighorn Sheep Disease Transmission Research

June 23, 2006 - Grazing policy is an important issue for sheep producers. Major land-use restrictions have been imposed in an effort to prevent domestic sheep from co-mingling with bighorn sheep because of an assumption that domestic sheep transmit pasturella to bighorns.

There is conflicting research on the cause of the disease and the high mortality rates in bighorn sheep, yet regulators are deciding federal grazing policy as if the scientific evidence is clear. Early field studies of bighorn die-offs concluded that pasturella transmission occurs between domestic and wild sheep. Industry experts, however, believe these studies are flawed and too narrowly focused and that new, unbiased studies must be conducted to provide conclusive documentation of the causes of bighorn deaths, as well as how bighorns might become exposed to pasturella.

The American Sheep Industry Association (ASI), along with the Public Lands Council (PLC), is working to assure that future research is directed toward the examination of the vulnerability of bighorn sheep as well as the many sources of pasturella and other respiratory diseases present in the environment and multiple species of animals. Improved scientific documentation of the health risks of bighorn sheep would be beneficial to policy makers in drafting more balanced federal grazing policies.

In a meeting last week, James Tate, Jr., Ph.D., science advisor to the secretary of the department of the interior, urged the industry to help coordinate research with that of the United States Geological Survey (USGS).

According to Tate, "Working with this entity can go a long way in demystifying pasturella transmission and is a good place to begin solving the issue."

Don Knowles, DVM, Ph.D., research leader at U.S. Department of Agriculture's Agricultural Research Service's Animal Disease Research Unit, also met with Tate. He is working with various other research agencies toward the implementation of new research approaches that should yield data that can be utilized by federal policy makers in regard to livestock grazing policy.

"The existing research does have some voids that need to be filled, such as the reasons for sensitivity of big horn sheep to disease and multiple species transmission," commented Knowles.

Staff contact: Tate Rosenbusch

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