Trichomoniasis – The Silent Infection

By Wesley Hood DVM, Pro-Vet of Siloam Springs, Ark.

Much has been said over the past few years about Trichomoniasis or “Trich” as it is commonly referred to. However, there is still confusion and mystery surrounding exactly what it is and more importantly what it can do to decimate your herd. In the next few minutes of reading, hopefully those questions can be cleared up in order to help protect your herd from this silent infection.

Trichomoniasis is a disease caused by the protozoal organism Tritrichomonas foetus. The organism lives in the preputial folds of the male and around the cervical folds of females. It is considered a sexually transmitted disease, as bulls contract the infection from infected cows during breeding or vice versa. The organism is virtually undetectable in bovine semen evaluations, causes no harm to the fertility of the bull and has no obvious signs of infection in cows or bulls. Cows that contract the infection can clear the organism in about five months, however most bulls are considered permanently infected and cannot be salvaged. There is a very small percentage of bulls under three years of age that may clear the infection after several months.

The disease process occurs as the organism infects the lining of the reproductive tract of the female and causes early embryonic death, mild uterine infections and sometimes early abortion of fetuses, typically in the first trimester. The bull does not suffer from infertility and is mainly an asymptomatic carrier of the organism. The overlying problem is the organism does not cause any visible illness in the affected animals and abortions occur early in pregnancy and are typically not observable.

The first sign of an infected herd starts with repeated heat cycles of females that should be already bred. A large number of females showing heat cycles late in the breeding season is a very common finding, as well as females that have been serviced early in the season rebreeding late in the season with no heats in between. The most confounding issue is by the time a problem is detected, it is normally too late to stop the repercussions.

The effects of Trichomoniasis can be crippling to a cow herd in conception rates. In herds with a defined calving season, conception rates can be decreased by up to 50% for that season. In herds that calve year round the effect can be seen as a high percentage of cattle calving every 18 months instead of every 12 months. Losing half a calf crop is obviously a financially crippling event. Not to mention the calves that do survive will typically be born much later in the calving season, decreasing weaning weights and subsequent rebreeding rates.

As detecting the disease is so difficult, focus must be taken on prevention of infection instead of treating an outbreak. There has been a large push by states in recent years to prevent the spread of this disease.  Almost all states have some type of Trichomoniasis testing protocols for both in state and out of state bull sales, both private treaty and auction. There are a few rules that are advisable when dealing with this disease. First and foremost is that ANY bull you use must be verified as a virgin bull with no breeding history or must be tested for Trichomoniasis prior to use in your herd. There are trusted individuals that sell many bulls private treaty that can be verified as virgin bulls. However, if there is any question, have the bull tested by your veterinarian BEFORE placing with cows. Testing involves scraping the inside of the preputial folds and sending either a culture or PCR test to a laboratory for analysis. A single PCR test is satisfactory for most state requirements and is required by most states to travel across state lines if the bull is over 12 months of age.

Prevention of the disease also involves screening any cows that are purchased out of herd.  Unfortunately, testing of cows is not as efficient or accurate. Therefore the easiest way of prevention is to buy cows or heifers that are bred greater than four months, verified virgin open heifers or pairs that have not been exposed back to a bull. The chances of Trichomoniasis being present in these groups is extremely small.

One of the main culprits of transmission is one that is hard to control. It has been said that good fences make good neighbors and this is extremely accurate in Trichomoniasis prevention. Some of the worst cases that have been seen involve the “traveling animal” whether male or female. If a neighbor’s farm is infected with Trichomoniasis and one of their animals is allowed to breed with one of yours, the results can be disastrous. It is imperative that you maintain strict biosecurity levels in your breeding herd and prevent introduction of this disease.

In the event your herd does become infected, there are options for control. The first is all natural service bulls will most likely have to be sold. There is a chance some bulls will escape infection, but it will require three negative tests over a period of a few months to insure that. All cows must be held from breeding for a minimum of five months in order to clear the infection naturally. There is also a vaccine available that is somewhat effective in decreasing embryonic losses and is typically used in trying to clear already infected herds. Above all, please discuss with your local veterinarian if you suspect Trichomoniasis in your herd. Early detection is the key to keeping the economic losses manageable.