Research conducted on M.ovi may turn up ways for domestic, wild sheep to share the same plains
Mycoplasma Ovipneumoniae (M.ovi) are two long words that have caused a lot of hate and discontent among people with sheep interests in the Western United States, according to one South Dakota State University researcher. The bacteria is a very small organism that inhabits the nasal cavity and respiratory tract of wild and domestic sheep and goats, according to Laura McHale.
“It is often spread through nose to nose contact or close contact with animals through projectiles like sneezing and nasal discharge,” she said.
The M.ovi debate centers around grazing domestic sheep and goats on public lands. It has caused a lot of problems for domestic sheep producers, especially in states like Idaho, Montana and Wyoming, where there are more public lands. “If a state has domestic sheep and wild sheep, there has been an issue. Wild sheep interests have worked very hard to get domestic sheep producers off public lands. In many cases, they have been successful in taking away government allotments for domestic sheep,” McHale said.
When a group of wild sheep get M.ovi, the impact can be significant, McHale said. “In wild sheep, it almost always results in some degree of pneumonia. Animals that survive will become carriers, and some will become shedders. They will sneeze and have nasal discharge. In ewes that lamb, it can cause lamb mortality,” she said. “We have seen that in the Pine Ridge area of Nebraska. In 2016, 2017 and 2018, every Big Horn sheep lamb has died, which is an average of about 45 of them. Not every one of them was from M. M.ovi, but a large proportion of them were.”
McHale’s research project, which is federally funded, is looking at the presence of M.ovi and its strain types in domestic sheep herds. The project will also attempt to identify factors that may influence respiratory disease prevalence in domestic sheep herds.
The project started last year and will finish up in June 2021, in the Wildcat Hills and Pine Ridge areas of Nebraska. “There are a lot of questions about contamination from Big Horn Sheep to domestic sheep, and vice versa. This study initially involved 100 head of sheep in Pine Ridge and 100 head in the Wildcat Hills. Currently, we have 36 producers and 330 sheep involved in the project,” McHale said.
The producers and sheep participating in the project maintain complete anonymity. “In my research, everyone cooperating in it has total confidentially. There are no costs involved to the producer. Producers get copies of all the test results. There is no record of producer by name, or by specific geographic location. I code every producer and each of their sheep,” McHale said.
The research is in three parts. The first is collecting nasal swabs by swabbing the nostrils with a Q-Tip. She also swabs the throat for presence of secondary bacteria. “Typically, we test every animal in the flock, and I usually do it when they are running them through for something else. I send in a random sample and store the rest. If there is an outbreak, we can pull more samples and get them tested. If there is a positive sample, the lab will strain test it,” she said.
McHale also records general data about each animal like age, sex, body condition, and health issues. If it is a ewe that will lamb, she collects information on the lamb, like birth weight, and if it is a single, twin, or triplet. “I may also go back and perform additional testing if the lamb is sick or a producer is adding animals to the flock,” she said.
If there is a death, McHale also goes back to take more nasal samples and collects three lung samples. “The lab can test lung tissue to determine if there is significant lung changes that have caused the mortality,” she said. Typically, she can have the results within seven to 10 days, although the strain testing can take longer.
The second part of the research is a disease ecology survey, which is a three-page survey that lists factors that may be contributing to M.ovi like pasture, feed regimens, antibiotic use and density of sheep. The third part of the research is the human dimension survey, which is conducted to gauge opinions and attitudes of sheep producers about M.ovi.
With less than 2.8 percent of public land in Nebraska, McHale said conducting a study like this has been very beneficial. “In Nebraska, no one can tell you what to do with your sheep or goats. Other states aren’t so lucky,” she said. Idaho has 75 percent public land and Wyoming has 50 percent. “There are a lot of people out there sympathetic to wild sheep and trying to get domestic sheep off public grazing lands. The Nebraska Game and Parks Commission has put a lot of effort into studying M.ovi in wild sheep, and they also collar them so they can monitor what is causing their mortality. The bottom line is in Nebraska, it doesn’t matter who gives it to who. Domestic sheep and wild sheep are closely related, and if a domestic sheep comes up to a wild sheep, it will spread from one to the other. It isn’t either ones fault, it’s just biology,” she said.
Does the future of M.ovi include vaccine development?
In February, the NGPC captured seven ewes in Pine Ridge that have tested positive every year for M.ovi. “They were probably shedding the bacteria, and were probably responsible for the deaths of the lambs,” she said. These ewes, who were deemed chronic carriers, have been taken to SDSU for more testing. McHale said they may be used for the future development of a multi-strain vaccine that could help future survival of both domestic and wild sheep.
“In Nebraska, we aren’t looking to get rid of domestic sheep. We just want to remove M.ovi, so we can have domestic sheep and wild sheep on the same landscape. Instead of declaring war on each other, it would be better if we could declare war on M.ovi,” she said. ❖
— Clark is a freelance livestock journalist from western Nebraska. She can be reached by email at firstname.lastname@example.org.