Trichomoniasis has been spreading around the country, even to areas where it typically hasn’t been seen. Testing bulls for the presence of Tritrichomonas foetus is becoming regulated on many state levels concerning bulls crossing state lines.
Trich testing of bulls, however, can cause injury to valuable bulls if not done carefully and correctly. David Anderson, DVM, MS, Dipl. ACVS, Kansas State University, says many veterinarians have been encouraged to be fairly aggressive when doing Trich tests using the dry-scrape method. “The thought is that you have to get ‘down to blood’ to achieve a truly diagnostic sample,” Anderson explains. “This increases the discomfort for the bull and may lead to inadvertent injury.”
Speaking at the 2012 Bull Management conference at Kansas State University, Anderson says if the AI pipette is applied too firmly, especially if the bull is uncooperative, the pipette can be pushed out through the fornix (the reflection of the prepuce onto the penis).
“This reflection is essentially a blind sac and if the tester applies too much pressure or the bull reacts violently to having the scrape done, the pipette can puncture through the prepuce,” Anderson notes.
“This causes inoculation of bacteria and debris into the tissues behind the fornix and can lead to an abscess. An abscess in this location can cause permanent injury to the prepuce and penis resulting in the bull losing his ability to extend the penis. If this happens, the bull may not only be lost to natural service breeding, but may also be lost to semen collection.” In that case, he says, a $600,000 bull can become a $0.32 per pound carcass.
Often, you can tell the procedure has gone wrong by blood dripping out of the prepuce. The examiner may feel the pipette suddenly push forward as resistance is lost after penetration of the prepuce at the fornix.
Blood isn't a goal
Anderson says veterinarians are taught to scrape until they get blood so that you know for sure that you have gotten to the level of the “crypts” in the prepuce. “This is thought to give the best chance of detecting a positive bull. This thought is similar to skin scraping – if you don’t get blood, you have not gone deep enough. We do not think that is true, or at least think it can go too far too easily.” The goal instead, he says, is to get smegma (preputial debris) from which to isolate the trichomonads.
Anderson offers these tips:
1. Properly and securely restrain the bull. Uncooperative bulls increase the risk of the test. If the bull is out of control, so can be the tester. Restraint can be improved using bull chutes, a tail jack, a flank rope or sedation.
2. Good lighting. If you cannot see what you are doing, it is hard to control the quality of what you are doing. Wear a head lamp to improve the lighting at the prepuce.
3. Gentle touch. It does not take an aggressive hand to get a good sample. Adequate volumes can be gained by being patient and persistent. Accidents happen fast. Slow and steady wins the race.
4. Have help. Use help when you have it! Take the time to train people how to help. Making plans on the fly can backfire.
A better tool
Anderson has recently started using the new Trich sampling pipettes, TrichitTM, from the Williams Co. in Lincoln, Neb. These tubes collect the sample while being pulled out rather than while being pushed in. The unique design at the tip of the pipette pulls the smegma down into the tube as it is withdrawn.
“This makes it less likely to induce trauma,” Anderson says. “We have been extremely pleased by the volume of sample we get and the ease of getting it. The added cost is reasonable give the reason for doing the test to begin with.” Visit www.trichit.com.