Finding answers Bighorn Sheep/Domestic Sheep Working Group looks at research

Lander – “Statements used to describe pneumonia in domestic lambs parallel what is seen in Bighorn sheep lambs,” Washington State University Researcher Maggie Highland commented during the Nov. 29 meeting of the Wyoming Bighorn Sheep/Domestic Sheep Interaction Working Group.

Highland continued, “An Iowa State University dissertation from the later 1990’s said, “The etiology of pneumonia in lambs is considered to be extremely complex as it relates to management practices and the disease.”

Highland added that, though the dissertation is over a decade old, the assertion still applies to both domestic sheep and Bighorn sheep, in general.

Disease foundations

Highland noted that there are three components to consider when looking at infectious diseases – the bugs, the beast and the burden.

“The bugs are present, and they are what introduces the disease,” she explained. “Then there’s the beast, whether they be sheep or goats, wild or domestic.”

Finally the burden is defined as the stressor, or any environmental situation that the animal perceives as being stressful enough to create a physiological change in the body as a response, either as a danger or as an excitement of some sort.

“I think that the research that is being done is trying to bring all these components together, rather than saying it’s just the bug,” Highland said.

Delving into the bug

While there are other factors that create disease, Highland noted that the bug often implicated in pneumonia in sheep, both domestic and wild, is Mycoplasma ovipneumoniae.

“I consider M. ovipneumoniae to be the most epidemiologically sound agent, and it’s also the agent of pneumonic disease in domestic sheep and goats,” Highland explained. “It is also believed to be species-specific, meaning it is only in members of the sub-family Capernaum, or goats and sheep.”

The bacterium has been discovered to be highly associated with the complex phenomenon of Bighorn sheep pneumonia, and Highland added, “It is often the predisposing factor that can set up sheep for more virulent or more pathogenic disease-causing problems, which are the secondary bacteria.”

Research

In light of the research efforts that have already been pursued, Highland noted that her lab has received funding for the next five-year budget cycle to identify host factors and the immuno-pathogenesis of pneumonia in Bighorn and domestic sheep.

“We’re looking at host genetics and shedding of M. ovipneumoniae, which includes how each species, on a cellular and molecular level, responds to infections,” Highland said. “We will look at both the innate and adapted response to infection.”

She continued that her research team has focused on domestic sheep and has been collecting samples for several years now.

“We’re also looking at the innate and adaptive immune factors dealing with susceptibility,” Highland added. “The last part of our research is looking at vaccine development against M. ovipneumoniae.”

Confusing samples

“I talk about confirmed positives,” Highland said. “The reason I say this is because of the difficulty in testing samples and the techniques we use.”

Highland noted that late last year she believed she had identified M. ovipneumoniae in white-tailed deer. However, the current analysis technique amplifies bacteria that is similar to M. ovipneumoniae but is not a Mycoplasma.

“It’s another Mycoplasma that has not been identified,” she explained. “I have found it in multiple goats. I also tested 98 elk, and of those, 87 were positive for this organism.”

She further emphasized that they must be very careful to make sure that a positive test is a true positive, not a similar organism.

Continued efforts

“The more minds that work together from different angles, the better,” Highland concluded. “As it pertains to Bighorn sheep conservation, we’re legally bound to collaborate or interact with the Forest Service and Bureau of Land Management as far as it pertains to management of Bighorn sheep in the sense of disease and disease transmission.”

She added, “When we have multiple people working different angle and good communications, we can reach out to one another to find the answers we’re looking for.”

Saige Albert is managing editor of the Wyoming livestock Roundup and can be reached at saige@wylr.net.