Flock and Herd logo

CASE NOTES

An outbreak of trichomoniasis in the Bingara District of NSW

Ted Irwin BVSc MANZCVS BA, District Veterinarian, North West LLS (Warialda)

Posted Flock and Herd August 2025

INTRODUCTION

Over the past 18 years I have had many enquiries related to poor reproductive performance in cattle. The enquires have varied from commonly reported single-observed abortion, to reduced pregnancy rates at pregnancy testing, abortion storms and stillborn calves in heifer mobs. As a veterinarian we are primarily concerned with diseases of livestock and so often put disease issues at the forefront of investigations which can be costly to work up thoroughly. The following case describes the history and approach to just one of these types of cases but for which a diagnosis was found in a timely manner and appropriate action taken to resolve the situation.

HISTORY

In March 2025 a Private Practitioner contacted the LLS about some poor pregnancy testing results. The vet involved had pregnancy tested 4 mobs (a mix of Speckle Park and Angus cows) and these were the results:

Joining period for these mobs was from September 2024 until the end of February 2025. Feed conditions were good. Notably the private practitioner noticed several pyometras in the cows. Condition of the cattle, length of joining, feed conditions, and bull power/functionality at the time could not account for these results.

A visit occurred the same afternoon and samples were taken from 7 cows (6 empties and 1 PTIC) which included cotton bud vaginal swabs (long-stemmed cotton tip swabs same as for footrot sampling) for PBS and PBST ((trich and Campylobacter (vibrio) media)) and also similar swabs in the dark yellow media (TFEM) for trich culture. Clotted and EDTA blood samples were collected in addition.

The pregnancy testing results were very suspicious for a disease process. A number of different mobs and different bulls were involved suggesting a bull problem was less likely. Due to the long joining period, it is uncertain whether this was a failure to conceive or early to mid-term abortions. No foetuses were ever seen on the ground.

Of the infectious causes of sub-fertility, the results seemed worse than would be expected for vibriosis or pestivirus. Neosporosis has never been diagnosed in this region and so was considered also unlikely. The fertility results and the presence of pyometras was heavily suggestive of Trichomoniasis and so the first tests were aimed at this disease. The PCR test was preferred due to its higher sensitivity compared to the TFEM culture media.

LABORATORY RESULTS

The PBS swabs for Trichomonas foetus (T. foetus) returned 3 out of 7 positives (2 empties and the 1 PTIC cow was also positive for Trich). This seemed enough for a diagnosis and no further testing was undertaken on those samples.

Subsequently 12 bulls from this producer, spanning 2 different properties were tested via the tricamper method (ribbed swab up the prepuce) in PBS. Four out of 12 bulls initially tested positive. Two other bulls were culled for age leaving 6 bulls. A re-test was recommended and of the remaining 6. One bull was absent from re-test whilst another bull was found that was missing prior so 6 bulls were tested, with only 5 of these being a re-test. Results at the time of writing are still pending.

DISCUSSION

T. foetus is an obligate protozoan parasite which makes a positive test result significant. In determining a diagnostic plan, the PCR for trichomoniasis seemed the most logical step due to its predicted high sensitivity. Of note would be that the texts suggest the PCR sensitivity and specificity is equivalent to the use of the T. foetus enrichment media (TFEM). I would suggest my confidence sways much more towards the PCR as less likely to produce a false negative result. Transport of the samples was delayed for some days post sampling (both bull tests were taken on a Friday) and it is suggested that sensitivity declines with storage. This is of definite concern moving forward with this herd and a final test before joining will be recommended with samples to be sent directly to the lab.

No further exclusion testing for other pathogens was undertaken and a thorough investigation might also look to exclude secondary contributing pathogens.

T. foetus is an uncommon cause of abortion. Generally the organism leads to low-grade endometritis which results in early embryonic death and resorption. Early to mid-term abortions are rare but can occur.

The common suggestive clues include - very poor detectable conception rates at pregnancy testing; detection of a high percentage (5-10% at times) of pyometras; detection of a mucopurulent discharge on return to oestrus.

Resolution of the disease in cows is spontaneous, but time varies. Some reports suggest as little as 2-3 cycles whilst others suggest 3-5 cycles are required to clear the infection. Regardless of this, cows that fail to deliver a calf but are held over to the next breeding season are considered a large risk of re-transmitting the infection and so the length of carrier status in cows can be uncertain.

In addition to this, immunity is short lived and so all animals are potentially susceptible during the next joining period. Malmo et al. suggests that cows redevelop immunity quicker and therefore maintain a pregnancy earlier than heifers infected for the first time.

Of note to veterinarians is the obligations under the Biosecurity Act 2013 for producers of infected cattle but also suspect cattle. Along with working with a veterinarian to eradicate the disease, a producer should provide a Health Certificate when selling or agisting cattle that indicates the cattle have come from an infected or suspect herd for trichomoniasis.

REFERENCES

  1. www.dpi.nsw.gov.au
  2. Parkinson T, Vermunt J, Malmo J, & Laven R (2019) Diseases of Cattle in Australasia (2nd ed.) Massey University Press
  3. www.mmsdvetmanual.com

 

Site contents Copyright 2006-2026©