Trichomoniasis is a venereal disease of cattle that is commonly seen in open range beef operations or in dairy herds that use bulls rather than artificial insemination.
It was first described in France in 1888, although it was not recognized as a common problem in western Canadian herds until 1993 when it was diagnosed in bulls from a community pasture in southern Saskatchewan.
Six percent of Saskatchewan bulls tested through the diagnostic lab in the following year were positive for the parasite.
We continue to diagnose trichomoniasis on the Prairies, especially where communal grazing is practiced.
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The disease can result in devastating reproductive losses that cause significant economic hardship.
The single celled parasite, called Tritrichomonas foetus, or T. foetus, lives in the prepuce of bulls and the reproductive tract of cows.
Mating is the only way to transmit the infection.
An infected cow can pass the parasite to a clean bull and an infected bull can pass the parasite to a clean cow. Older bulls are more likely to be infected, but young bulls are not exempt.
There is some evidence that bull to bull transmission is possible, but the evidence is not clear cut.
Transmission through artificial insemination is unlikely, although the parasite can be preserved in frozen semen. Semen companies in the United States and Canada must regularly test bulls to sell semen.
Bulls are the long-term carriers of the disease and are usually infected for life. Infected bulls will display no clinical signs of infection and will have normal semen when tested. Slaughter is the only solution for infected bulls.
All ages of breeding females are susceptible to infection.
An infected cow may conceive normally, but its immune system creates an inflammatory reaction to get rid of the parasite.
This inflammation may be what causes the death of the embryo and the loss of the pregnancy.
Pregnancy loss usually occurs at less than 60 days gestation, so it is often not noticeable by the producer. The cow eventually comes back into heat but it may take two to six months after the infection to restore fertility in the cow.
Cows will usually clear the infection in two to four months but they have a short lived natural immunity and may become infected again in subsequent breeding seasons.
Herds that have become infected with T. foetus often have a high percentage of open cows or late pregnancies.
There may be occasional abortions at less than five months gestation or a few cows with evidence of pus in their uterus at pregnancy checking time. There will be no clinical symptoms in bulls.
Vibriosis, or campylobacter foetus, another venereal disease caused by a bacterial infection, may have similar symptoms.
A veterinarian can help diagnose trichomoniasis by testing your bulls for the infection. The diagnostic tests for the parasite are not especially effective in cows, and so we focus our diagnostic efforts on the bulls.
A cow that has successfully calved and has its calf at foot is almost certainly free of T. foetus.
As a result, we cull open cows and test bulls to eliminate the infection from the herd.
Diagnostic tests include traditional culture and polymerase chain reaction (PCR). None of them are perfect and in some situations bulls may require three diagnostic tests to ensure they are negative.
Controlling trichomoniasis is effective if a few simple rules are followed.
Community pastures that adopt these guidelines have been successful in eliminating the parasite and keeping their pregnancy rates high.
It is important to identify the problem as early as possible, which means pregnancy checking cows helps provide an early warning system for fertility problems.
Ensure that bulls are clean by using culture or PCR testing to cull and eliminate carrier bulls with the parasite. Only virgin bulls or bulls that have been tested can be allowed onto the breeding pasture.
Allow only virgin heifers and cows that have successfully calved and have a calf at foot onto the breeding pasture to ensure that cows are uninfected.
Practice good biosecurity by wintering bulls away from the cow herd and avoiding buying bulls and cows with an unknown reproductive history.
John Campbell is head of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.
