Veterinarians across western South Dakota are continuing to test herds for a reproductive disease that causes cows to abort their young, though officials say no new cases have been reported over the past month.
The most recent cases of bovine trichomoniasis — or trich — were discovered in January in a pair of herds in Dewey County. Late last year, vets found trich in two Oglala Lakota county cattle herds and one herd operating in Corson and Ziebach counties, said Mendel Miller, South Dakota's assistant state veterinarian.
Miller said he doesn't expect an outbreak like one that hit western South Dakota in 2005, but the five occurrences are a jump from zero cases last year and just one the previous year.
The disease poses no risk for humans, as it affects only a cow's reproductive system, but its occurrence can quickly cut into a rancher's bottom line.
"We have lots of testing going on," Miller said. "Neighbor herds, contact herds are testing and looking for it."
Beth Carlson, North Dakota's deputy state veterinarian, said no cases have been reported there, and the state hasn't seen instances of the disease for several years.
Ranchers are often unaware of the problem until the disease is well established in the herd. Some signs that the disease may be present in a herd include a high number of open cows, cows showing signs of heat when they should be pregnant and the presence of many late-calving cows, according to the Animal Industry Board.
"Many producers pregnancy test their cows in the fall, so if they did have a number of cows that have aborted or were not pregnant, they probably already found out," Miller said. "If they did not pregnancy test, then they would be finding out here pretty soon."
South Dakota's 2005 outbreak — in which vets confirmed 45 cases of the disease, all west of the Missouri River — prompted the Animal Industry Board to issue several testing rules to prevent its spread. Those rules greatly reduced the occurrence of the disease, officials say, but trich can occur in remote areas where the separation of bulls doesn't always happen.