OMAHA, Neb. — The prevalence of trichomoniasis is probably low, but the results are disastrous if this venereal disease appears in a cow herd.
“I can assure you if you or your neighbours have it, prevalence doesn’t matter. It is a big deal,” said Jeff Ondrak, a bovine veterinarian at the University of Nebraska’s Great Plains Veterinary Educational Centre.
“If you have cows, and 50 percent of your cows are open, trich is a pretty important disease to you.… It is assumed somewhere between 80 and 90 percent of cows exposed to trich positive bulls get infected.”
Recently published research in the Journal of Veterinary Diagnostic Investigation estimated prevalence at 5.5 percent in Texas herds but probably as high as 30 percent in Florida.
Bulls carrying the protozoa in their genital tract spread disease when they breed. The cows lose the fetus at 50 to 80 days, but late term abortions have also been reported.
The cow clears the infection and cycles again, but chronic and persistently infected cows can be a problem.
The disease has been known since 1888, when fertility problems were noted in France. It had spread worldwide by 1920 and first appeared in the United States in 1932.
“Most vets will say trich is a problem that pops up every 10 years or 15 years,” Ondrak said at a trichomoniasis meeting held during the National Institute for Animal Agriculture convention in Omaha April 1-4.
“They don’t get excited about it and it dies down.”
The male shows no clinical signs.
Researchers believe bulls develop crypts in the prepuce as they age, which allows the infection to live on and continue the infection.
The tip of the penis has the highest amount of the parasite, according to Ondrak’s most recent research.
Chronic carriers are usually bulls three years or older.
There is no treatment, so positive bulls need to be slaughtered. Vaccines have been developed with limited success.
“It will reduce pregnancy loss related to the disease. For people in high risk areas or they have a neigh-bour who is unwilling to deal with trich, the vaccine may be useful,” he said.
Bulls need to be tested, but there have been complaints with poor testing technique, information misread at laboratories and false positive or negative results.
Testing requires collecting and culturing smegma from bulls and then examining it in a laboratory. Smegma is a cheesy collection of cells gathered from around the prepuce.
Chances of detecting the parasite increase if the bull is separated from cows for at least two weeks before testing.
Trichomoniasis is a notifiable disease in Canada, where its presence is acknowledged but no immediate actions are taken.
The Beef Cattle Research Council has a video available at www.beefresearch.ca/research-topic.cfm/reproductive- failure-3.