Dakota Farmer

State veterinarian issues warning about reproductive disease and suggests that bulls be tested before the breeding season

April 4, 2016

2 Min Read

There’s been a resurgence of trichomoniasis, a reproductive disease of cattle, in South Dakota since 2015, says Russ Daly, South Dakota State University Extension veterinarian.

“Cattle producers should keep the disease at the top of their mind when preparing for the upcoming breeding season,” he says.

Trichomoniasis has been around for generations, but for many years it was thought to be something only states west of the Rocky Mountains had to concern themselves with. That changed for South Dakota cattle producers back in 2004, when more than 40 herds were detected with the disease and were faced with the task of cleaning it up.

A cooperative effort between the South Dakota Animal Industry Board and cattle producer organizations resulted in the implementation of regulations that not only tackled importation of the disease, but also reduced the spread of the disease within the state.

These regulations involved testing of all non-virgin bulls moving into the state or between herds, as well as the prohibition of open cows being sold back into breeding herds.

"Since 2005, South Dakota enjoyed years of very few new infections, however beginning in late 2015, several newly infected herds have been identified. Counties recently affected include Corson, Dewey, Gregory, Mellette and Oglala Lakota," Daly says. "Whether this represents an incursion from other parts of the country or a resurgence of a previously undetected problem is uncertain."

Trichomoniasisis caused by a protozoal organism that lives indefinitely in the sheath of an infected bull. Once it's transmitted to a female through the act of breeding, it causes an inflammation in the reproductive tract that results in the loss of the pregnancy. While infected cows can clear themselves of the infection, bulls remain positive for life.

Therefore, Daly said detection strategies for this disease come down to testing the bull.

For testing bulls, the preferred sample is still a scraping from inside the animal's sheath.

"This is where the protozoa live, protected by the microscopic peaks and valleys in the skin inside the sheath," he says.

The most commonly used lab method for trichomoniasis detection is polymerase chain reaction (PCR) testing. "This is a very sensitive diagnostic technique that can detect just a few organisms, as well as those that are no longer living," he says.

The culture method previously used was fraught with enough short-comings that veterinarians were required to take three samples at weekly intervals from the bull in order to ensure that an infection was not missed. In contrast, only one sample is required from a bull if PCR is used.

Overall, Daly said that improvements in test sensitivity and in awareness of have significantly reduced the risk of its introduction into our cattle herds overall. 

However, trichomoniasis is a long way from being eradicated and will remain a consideration for cattlemen for a long time to come, Daly says.

Source: SDSU Extension

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