Trichomoniasis (Trich) is a sexually transmitted disease caused by a parasite that causes infertility and abortions in the first trimester. All states neighboring Kansas, and most states further south, west and north of our neighbors now require Trich testing of bulls prior to importation into the respective states. A number of Kansas producers have experienced reproductive problems of the nature that made them or their veterinarians suspect and test for Trich. As a result of this testing, numerous new cases of this sexually-transmitted disease have been discovered in Kansas during the past year. Counties shown in green below are counties from which the Kansas Veterinary Diagnostic Laboratory has reported positive samples being submitted as of November 21, 2011.
Many producers have asked about the use of vaccines to prevent Trichomoniasis. Trichguard®, a vaccine marketed by Boehringer-Ingelheim, is commercially available for such use in cows. This vaccine does not prevent infections, but will reduce the incidence of early embryonic death and abortion associated with trich in cows. Information submitted to U.S.D.A. for vaccine licensing purposes indicate that use of this product improves pregnancy rates less than 80 percent when compared to unvaccinated controls, resulting in a label claim stating that it “serves as an aid in prevention of disease”.
In one controlled challenge study in Nevada where both vaccinated and non-vaccinated heifers were bred by Trich-positive bulls, 62 percent of the vaccinated heifers calved while only 31 percent of the non-vaccinated heifers calved. 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. For proper use of the product, two injections 2 to 4 weeks apart are required in cows, with the second injection given 2 to 3 weeks before bull turnout. Annual revaccination with a single injection is required. The vaccine does not provide long-term immunity; therefore, it must be given no earlier than 30 to 60 days prior to the start of the breeding season. One major concern with use of the vaccine is that it gives a false sense of security. Despite vaccination, the disease can persist in the bulls, which in turn allows the disease to persist in the herd, although at a lower level. Bulls from this herd may continue to infect those females that do not respond well to the vaccine, and may also be a source of infection for neighboring herds if bulls jump the fence and get into neighboring herds which are not vaccinated.
The major situation where Trich vaccination is a recommended management practice is when herds are being grazed together on communal pastures such as Bureau of Land Management (BLM) grazing leases. In this high-risk situation vaccination and using only tested Trich-negative bulls are two of the critical management factors under the individual cattle owner’s control. Trich vaccination should result in a higher percentage calf crop, but will still not be as high as in a situation where Trich does not exist.
Since bulls are the carriers and maintenance hosts of this disease, they are the focal point of concern relative to transmission of this disease. Using only virgin bulls or “experienced” bulls that have been tested and found negative for the disease are two primary management strategies for controlling this potentially financially devastating disease. As breeding soundness evaluations (BSE) are performed on bulls this winter/spring, testing for Trich should be included after it has been determined that each bull has passed the earlier parts of the BSE. Another strategy is not to buy open cows as replacements, unless they have a 5-month old calf at side and have not been exposed to a bull since calving. Maintaining good fences, or better yet, keeping breeding female groups in pastures that are out of sight of neighbors’ pastures where bulls are present, are also valuable components of an effective Trich management program.
Producers should be reminded that Trich is a reportable disease in KS. When a case is reported, a veterinarian from the Kansas Department of Agriculture will normally visit the operation to try to determine the source of introduction of the disease. Being a good neighbor suggests that the owner of a positive bull(s) should contact adjoining neighbors so that they will be aware of the presence of the disease in the area and determine if they need to have their herds tested as well.
Source: Larry Hollis, extension beef veterinarian