Trichomoniasis – May ’16

May 2016 Newsletter PDF

Trichomoniasis

by Carrie Bargren, DVM

Trichomoniasis, other than being an impressive word, is a venereal (sexually transmitted) disease in cattle caused by the protozoa Tritrichomonas foetus and is of great importance to bull-bred herds, dairy or beef. There are no outward symptoms of infection, rather the herd will develop a fertility problem.  All sexually active cattle are susceptible and the negative herd health impacts can be substantial, including fewer calves and a variation in calf size at weaning. The cost of a herd infection adds up as well, with animals in quarantine, testing and culling cattle and purchasing replacement bulls and heifers.

Tritrichomonas foetus is a pear-shaped parasite that is slightly larger than the head of a bovine sperm cell. It invades and colonizes the microscopic folds of the reproductive system in both cows and bulls. When an infected bull breeds an uninfected female, the organism in the prepuce and penis attaches to and invades the vaginal mucosa. It replicates and spreads throughout the entire reproductive tract in about 50-60 days, causing endometritis (inflammation of the uterine tissue) by killing cells and breaking red blood cells, which stimulate inflammation. Because it takes so long for the infection to spread, the cow is able to conceive from the breeding, but the infection and inflammation result in loss of the embryo. The cow will clear the infection in about 3 months, return to estrus and conceive normally, but will be late or short-bred. She will then calve much later in the spring, resulting in a low weaning weight of the calf. It is possible for a late term infection to cause abortion at 7-8 months gestation, but a failure to conceive is the most common sign of infection.

Trichomoniasis is transmitted from an infected bull breeding an uninfected female, but the bull acquires the infection from breeding an infected female. Older bulls are at the highest risk of infection, due to the high likelihood of breeding the most cows from multiple sources. An infected bull will have no outward symptoms, but occasionally have small nodules on the prepuce and a discharge. He is unlikely to clear an infection and should be culled to prevent spread of the disease.

While there are currently no federal trichomoniasis regulations, some states have controls on testing prior to animal movement, especially many southwestern and central plains states. There are no testing requirements for import into Wisconsin, but that doesn’t mean regular testing isn’t necessary and preventative steps shouldn’t be taken to reduce the risk of infection in the herd.

Testing bulls is quite simple. The organism can be identified by culture or DNA testing in the smegma or a preputial flush from the bull. Any positive cultures are confirmed with the DNA test. If there are multiple bulls from the same herd being tested, the samples can be combined. If the bull is from an area where it is prevalent, he should be tested annually at his springtime breeding soundness exam. The following is a list of examples when a bull should be tested:

  • Annually for herd bulls
  • Before introducing a bull for the breeding season
  • Before purchasing a presumed virgin bull
  • Poor pregnancy rate, extended calving period or  signs of abortions
  • After commingling the herd
  • After a break in the fence
  • After breeding season
  • After introducing open cows

Preventing the introduction of the organism to the herd is based around good biosecurity and management practices. AI does provide good control, but the semen can become contaminated at time of collection. Ask the bull stud about their protocol for trichomoniasis testing to make sure the cows aren’t bred with a possibly infected straw; most should have a protocol in place.

Most often, the disease is introduced through insufficient biosecurity: all new additions to the herd should be placed in quarantine to monitor for any disease, not just trichomoniasis. New bulls should either be known virgins <18 months old or test negative, once by DNA or three negative cultures, and keep them in quarantine until they test negative. Replacement heifers should be known virgins or over 120 days pregnant. After this stage in gestation, they would have cleared any possible infection. Any heifer under 120 days pregnant should be kept in quarantine until she is past that threshold. Place purchased open cows in quarantine for at least 120 days sexual rest to clear any possible infection.

Defining the breeding period provides a method of monitoring for potential infections in the cows. It should be 60-90 days. If a cow is infected during that time, she may lose the fetus, resolve the infection and be found open on palpation in the fall. A breeding period >90 days allows infected animals to clear the infection and be rebred within that time-frame, which will extend the spring calving period. Having your vet check all the cows for pregnancy in the fall will find reproductively unsound animals, possibly for a different reason than trichomoniasis, and the problem can be identified. If there are too many open or short-bred cows at that time, suspect trichomoniasis.

Maintain the fencing on pastures. Broken fences lead to unintended matings, inaccurate breeding records, undesired genetics and an increased risk of trichomoniasis being introduced to the herd from either an infected bull or cow. There is a vaccine for trichomoniasis, but it only reduces the severity of disease and is only cost effective for increased risk herds in prevalent areas.

Here is a list of management practices that increase the risk of introducing and spreading trichomoniasis in the herd:

  • Untested bulls
  • Undefined breeding season
  • Introducing open, late-bred cows/heifers to herd
  • Keeping non-pregnant animals into the next season
  • Commingling animals from different owners during breeding season
  • Keeping older (over 4-5yrs), untested bulls

As you begin to think about the next breeding season, consider testing your bulls for trichomoniasis during the annual breeding soundness exam. If you’re interested, call the clinic ahead of time so that the correct sampling materials can be ordered.


estroPLANning

The FDA approved estroPLAN in 2004 to induce luteolysis in cycling dairy and beef cattle. It has the same active molecule as Estrumate, cloprostenol sodium, an analogue of the natural hormone prostaglandin. The concentration of the cloprostenol in estroPLAN is the same, meaning the dose is the same as Estrumate, 2mL. The only difference? The price! estroPLAN is $0.24-$0.70 cheaper per dose than Estrumate.

The same company produces GONAbreed, which was approved by the FDA in 2013 for the synchronization of estrous for timed AI and the treatment of follicular cysts. This is different from Cystorelin, which is only approved for the treatment of follicular cysts. The active drug in GONAbreed, gonadorelin, is the same as in Cystorelin but at a higher concentration. Therefore it is only 1mL per dose, rather than the 2mL dose with Cystorelin. If you are worried about kickback of the drug with such a small dose, research shows that there is more kickback with larger doses. Small doses (1mL) have very little. GONAbreed is cheaper than Cystorelin but comes in larger bottles, 20mL (20 dose) and 100mL (100 dose). The chart below shows the prices per dose. If the large sizes of the GONAbreed bottles aren’t feasible, estroPLAN can be used in combination with Cystorelin.

Synch Drugs

Disclosure: neither the author nor RVVC received compensation from Parnell for this article.


MyAnimalRx

For those who call the clinic to order medicine and supplies for drop ship, you can now order them yourself online! If you’re interested, contact the Plain office and give them a current email address. They’ll start the registration process with MyAnimalRx and you’ll receive an email with instructions on how to complete it. You will then be able to place an order at any time, although all prescription drugs will need approval by RVVC after you order. It’s such a convenient way to order your supplies! Contact us to be enrolled or if you have any questions.

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