TRICHOMONIASIS: PART II Prevention and Control

Last month in this column we discussed the cause of Trichomoniasis in cattle and how it appears in a beef cattle herd when that herd becomes infected. Also discussed, was the method of transmission of the "Trich" organism. Remember, that the infected bull(s) that is showing no evidence of disease is the main means of transmission. Also, cows or heifers that become infected can spread the organism to uninfected bulls during breeding. Therefore, some cows in the herd can be a source of the organism for other members of the herd prior to the time those individual cows clear the "Trich" organism from their reproductive tract. The diagnosis of Trichomoniasis was reviewed and this month we will focus on control and prevention of this disease. If a diagnosis of "Trich" is made in your herd there are a number of questions that come up.

Is there a treatment for the bulls? Technically, ethically and legally, no. There is no FDA approved treatment for "Trich" in cattle. Several years ago, some bulls were successfully treated with a poultry product, but the drug is not approved for such use in cattle. Not only that, but the FDA has declared that the use of this poultry product in cattle is outright illegal.

What about the cows and heifers? Most studies have shown that the disease is self-limiting in the female. This is in contrast to the bulls, who can carry the "Trich" organism for years. After several heat cycles, most cows and heifers clean themselves up, but this may take months. Research is showing that up to six months may be required in some cases, but 1-4 months is more common.

Is there a vaccine? Yes. Fort Dodge currently markets a vaccine made from killed whole cells of Tritrichomonis foetus. Tests of this vaccine have shown that experimentally infected, vaccinated females "clear" a vaginal infection in a matter of a few weeks, whereas control (unvaccinated) females can remain infected for months. As of this date, no efficacy for bulls has been shown, i.e. the vaccine has not been shown to protect bulls from becoming infected. Also, vaccination of the bulls with the "Trich" vaccine will not eliminate the organism from the bulls.

At pregnancy check time, non-pregnant females, especially those with reproductive tracts that the veterinarian declares "abnormal" (e.g. with pyometra) should be sold for slaughter. Do not keep these females. They might represent "carrier cows" that could maintain the disease in the cow herd even if the bulls were cleaned up. Non-pregnant females with "normal" tracts may be kept over for re-breeding, if a "split" calving season is practiced. However, some of these open cows that feel normal may be infected with "Trich" for weeks to months. They should not be mingled with the normal, pregnant cows; nor should the same bulls breed these two different groups of cows. Alternatively, these open cows could be culled. It is important to understand that some cows in a herd with "Trich" could be a source of re-infection of that herd in the months after discovering the infection. Additionally, in some herd situations, artificial insemination can be used to clear up an infected herd and heat synchronization can be helpful in this regard.

What are some of the steps to prevent Trichomoniasis, if my herd's never had it?

1.Use young, fertile bulls (less than 3 years). Many studies have confirmed that younger bulls are less able to carry and transmit the disease. That is, younger bulls are more resistant to the "Trich" organism and are less likely to transmit this agent to the cow herd. Purchased bulls should have a breeding soundness examination, including a semen check and a "Trich" test, to be sure they are healthy and free of disease.

2.Keep fences in good repair. Good fences make good neighbors.

3.Culture new bulls and old bulls prior to the breeding season, at the semen exam time. This is also a good time to vaccinate bulls for Vibrio (another venereal disease).

4.Be very suspicious of new cows or bulls, especially somebody else's cull. Keep the cow herd closed and use only virgin and/or "Trich-negative" bulls whenever possible. Do not loan, rent, or borrow bulls.

5.If there is some risk of Trichomoniasis entering your herd, vaccinate females for "Trich", twice at 1 month intervals, then give annual boosters. The best time to vaccinate (or to give annual boosters) is just a few weeks before the bulls are turned in, so that immunity in the cows is high at the time of possible exposure to the "bug". It should be noted that if there is no risk of introduction of "Trich" to a closed herd, vaccination will not be necessary.

6. If cattle are run on open range, where there is a risk of introducing "Trich" into the herd, it may be advisable to adjust the breeding season/calving season so that the cow herd is pregnant when they go onto range. No breeding, no risk of "Trich".

7. Trichomoniasis is a complex disease problem and your veterinarian should always be consulted regarding decisions about preventing, controlling, or diagnosing this disease.

Robert BonDurant, DVM
Diplomate, ACT
Professor and Chair,
Department of Health & Reproduction
School of Veterinary Medicine

John Maas, DVM, MS
Diplomate, ACVN & ACVIM
Extension Veterinarian
School of Veterinary Medicine