Presence of Tritrichomonas foetus in a chronically infected bull’s urethra

A 5 year old Maine Anjou Angus cross bull was donated to Auburn University College of Veterinary Medicine. Bull’s smegma was collected via preputial scraping with an artificial insemination pipette attached to a 20 ml syringe. Smegma sample was placed into a vial with Modified Diamond’s media and submitted to Thompson Bishop Sparks Alabama state diagnostic laboratory (TBSASDL) for testing for Tritrichomonas foetus (T. foetus). Bull was positive for T. foetus DNA, based on real time polymerase chain reaction (RTPCR). Bull was tested for T. foetus on numerous occasions annually over a period of 5 years and was deemed chronically infected with T. foetus. Prior to euthanasia, smegma was collected and placed in Modified Diamond’s media. Bull and its smegma sample were submitted to TBSASDL for necropsy and RTPCR, respectively. Reproductive tract was dissected free; 1 x 1 cm sections were cut from prostate, right and left ampullae, right and left vesicular glands, and sections of urethra. The urethra was sectioned at specified locations; 5 cm proximal from distal end of urethra; 23 cm proximal from distal end of urethra; 5 cm distal to last bend of sigmoid; and 13 cm proximal to sigmoid and urethra at ischium level. All samples were placed in Modified Diamond’s media and submitted to TBSASDL for culture and testing for T. foetus DNA via RTPCR. Reproductive tract was sectioned from most proximal portion to most distal portion. Gloves were changed between each collection of tissue sectioned. Instruments were cleaned following collection of each tissue section to prevent accidental contamination. A new sterile blade was used when sectioning each portion of reproductive tract. Prostate, vesicular glands, ampullae, and proximal urethra were all negative for T. foetus DNA. Smegma from preputial scraping and urethral sections 5 cm proximal from distal end of urethra, and 23 cm proximal from distal end of urethra were positive for T. foetus DNA via RTPCR with a cycle threshold (CT) of 30, 34.3, and 36, respectively. CT values from 30 - 37 are considered a positive reaction, indicative of moderate amounts of target nucleic acid present in this case. This is first documentation of T. foetus in a more proximal location in urethra. A few studies identified T. foetus presence in distal urethra of some bulls, but not in every bull. However, those studies were performed prior to availability of PCR; therefore, there might have been some false positives from bulls tested. This case provided important information for researchers assessing clearance of T. foetus from infected bulls, as topical treatments alone will not be curative to all bulls.

Keywords: Cattle, trichomonias, Tritrichomonias foetus, urethra

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.