Disease Jumps From Domestic to Wild Sheep

More reporting about the bighorn/domestic sheep disease study

Other than the study itself, this is the first time that I’ve heard Dr. Srikmaran talk about last year’s study which confirms that domestic sheep diseases kill bighorn sheep.

“I am not that happy about this finding. Some people’s livelihood depends on domestic sheep,” [But the] “organisms did not exist anywhere else. They could only come from one place, the domestic sheep.” – Dr. Subramaniam Srikmaran

Some people who support the sheep industry have made misrepresentations of what the study actually says. They say that “these data show that even extended fence line contact of 2 months didn’t lead to disease and death. Disease required co-mingling for a minimum of 48 hours and this was after transmission had already occurred in three of the bighorn sheep.”

I’ve had the chance to read the study and, in fact, it does not say that it took two days of commingling to produce disease. It says that one of the sheep died within two days of the beginning of commingling portion of the experiment. All four of the bighorn sheep, even the one which did not contract M. haemolytica during the fenceline portion of the study died within 9 days of the beginning of the commingling portion of the study. There is no evidence to support the claim that “disease required co-mingling for a minimum of 48 hours”.

The study even says that:

“It is conceivable that the bighorn sheep that acquired the tagged M. haemolytica during the fence-line contact would have died even without commingling with the domestic sheep.”

Furthermore, there is no evidence that “if left at fence-line contact the bighorn sheep would have developed immunity instead of disease”. The study actually states the opposite may be true:

“This notion is supported by the fact that one bighorn died only 2 days after commingling with the domestic sheep.”

It’s almost as if the sheep industry wants us to believe that these pathogens just appear out of nowhere as postulated by the theory of spontaneous generation. These pathogens don’t just live in the dirt and spring forth to cause disease, they must have a host and that host is domestic sheep and goats.

The story also has a short video of a coughing bighorn sheep.

New Evidence: Disease Jumps From Domestic to Wild Sheep
Oregon Field Guide.


  1. Larry Thorngren Avatar

    The video is really sad. Frank Shirts and the rest of Idaho’s Woolgrowers should have their herds of domestic sheep banned from grazing on public lands.
    The Forest Service requires that hay used on public land be “Weed Free”. Shouldn’t the domestic sheep grazing on public lands be required to show they are “Disease Free”?

    1. jdubya Avatar

      Larry, good point. I wonder what it would cost and if it would be possible to derive a haemolytica-free sheep herd.

  2. Ralph Maughan Avatar

    To me, one of the most interesting general conclusions I have made about wildlife diseases, is their intensely political nature.

    The danger from these diseases to wildlife and to humans is regularly exaggerated or downgraded in order to serve the purposes of various groups.

    The danger from bovine brucellosis is greatly exaggerated, although a resurgence of interest in drinking raw milk could once again make the disease more of a danger to humans. Other kinds of brucellosis affect a small number of Americans, mostly a few immigrant populations.

    The danger from Echinococcus granulosis (a canid tapeworm) to humans is almost entirely fiction. No one who handles wolves in the United States and maybe elsewhere seems to have gotten it.

    On the other hand, the profound lethal effect of M. haemolytica on bighorn sheep from contact with domestic sheep was actually suppressed. In the short term, it is the single greatest threat and source of mortality to our bighorn sheep herds.

    Chronic wasting disease in deer and elk (and maybe some other animals, e.g.,) is their greatest disease threat. Its danger is widely recognized, but management changes to prevent its spread are very hard to accomplish because of livestock politics. The cause of the disease, a malformed infectious protein, is almost as persistent as radioactive contamination.


Ken Cole is a 5th generation Idahoan, an avid fly fisherman, wildlife enthusiast, and photographer. He is the interim Idaho Director for Western Watersheds Project.

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Ken Cole