Trichomoniasis in Ox: Venereal Infection, Infertility, and Testing

Trichomoniasis in cattle is a venereal, or breeding-transmitted, infection caused by the protozoan Tritrichomonas foetus. It is best known for reducing herd fertility rather than causing dramatic illness. Infected bulls often look normal, but they can carry the organism in the folds of the penis and prepuce and spread it during natural service.

In cows and heifers, the organism moves through the reproductive tract and can trigger inflammation that leads to early embryonic loss, temporary infertility, repeat breeding, and sometimes abortion. Many females eventually clear the infection after a period of sexual rest, but that recovery takes time and can still leave a herd with fewer pregnancies and a stretched-out calving season.

This disease matters most at the herd level. Pet parents and producers may first notice a problem when pregnancy rates drop, more females are open at preg check, or calves arrive over a much wider date range than expected. Because infected bulls usually have no obvious signs, testing and herd planning are central parts of care.

Trichomoniasis is caused by Tritrichomonas foetus, a microscopic protozoan parasite. The infection spreads mainly through natural breeding. An infected bull can pass the organism to cows and heifers, and infected females can also pass it back to bulls during breeding.

Older bulls are a major concern because the organism can persist in the deeper folds of the prepuce, making long-term carriage more likely. Younger bulls may clear infection more readily, but they can still become infected and spread it. In cows, infection often causes temporary infertility and early pregnancy loss, and most eventually clear the organism after several months of sexual rest.

Common risk factors include using borrowed, leased, or shared bulls, buying breeding bulls without testing, fence-line or accidental exposure to neighboring cattle, and breeding in herds with long or poorly defined breeding seasons. Artificial insemination can reduce risk when semen handling is controlled and the semen source is free of contamination.

Diagnosis usually centers on the bull, because bulls are the main long-term reservoir. Your vet collects a preputial sample, often called preputial smegma or scraping material, and submits it for PCR testing or culture. PCR is widely used in current control programs, while some states and situations still accept serial culture testing.

Testing is often done as part of a breeding soundness exam before turnout. USDA guidance recommends annual testing of herd bulls in areas where trichomoniasis is prevalent, ideally 60-75 days before cows and heifers are exposed. Some state programs also require a period without contact with sexually mature females before sample collection, and movement or sale rules vary by state.

Females are harder to use for routine diagnosis because infection may be temporary and organism numbers can be low. In practice, your vet may diagnose a herd problem by combining bull test results with herd history, pregnancy rates, calving distribution, and reproductive findings such as pyometra. Because trichomoniasis and bovine genital campylobacteriosis can look similar, your vet may recommend testing for both.

Prevention focuses on keeping the organism out of the herd and stopping it from cycling between bulls and females. The most practical steps are testing breeding bulls before turnout, avoiding borrowed or leased bulls of unknown status, and buying only virgin bulls or bulls with current negative official testing when allowed by your state. Many operations also test bulls before sale or interstate movement because state rules can be strict and vary by destination.

Good fencing matters. Fence breaks and contact with neighboring breeding cattle are common ways herds become exposed. If a breach happens, let your vet know quickly so they can advise whether re-testing is needed before the breeding season continues.

A defined breeding season can make problems easier to spot and control. Pregnancy checking helps identify open females early, and replacing natural service with artificial insemination in some groups can lower venereal disease risk when semen sources and handling are well managed.

There is no dependable treatment plan that clears infected bulls, and vaccine benefit is limited where products are available. That is why prevention usually comes down to biosecurity, testing, culling positives, and working with your vet on a herd-specific reproductive plan.