Study supports saline for Tritrichomonas foetus PCR transport

A new noninferiority study in the Journal of Veterinary Diagnostic Investigation found that 0.9% sterile saline performed comparably to phosphate-buffered saline, or PBS, as a transport medium for Tritrichomonas foetus RT-rtPCR testing at the assay’s reported limit of detection. In the Mississippi State University-led trial, the mean cycle threshold difference between saline and PBS was 0.19, and the confidence interval stayed below the prespecified noninferiority margin of 1.0 Ct, supporting saline as a practical alternative for preputial washing samples. The finding addresses a common field constraint: PBS is the medium originally validated for the assay, but it isn’t something many veterinarians routinely stock. (pmc.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals working in bovine reproductive health and regulatory testing, this could make sample collection more practical without meaningfully sacrificing analytic performance. That matters because T. foetus remains a costly venereal pathogen in cattle, and false negatives tied to transport or handling can have herd-level consequences. The broader testing landscape is already moving in this direction: Nevada’s animal disease lab began offering direct RT-rtPCR on PBS or saline collections in February 2024, and Texas A&M’s veterinary diagnostic lab lists direct smegma in PBS or sterile saline among accepted specimen types. Separate recent work also suggests both PBS and sterile saline can preserve samples during shipment under a range of conditions. (agri.nv.gov)

What to watch: Watch for whether more state and university diagnostic labs formally update submission guidance, official testing protocols, or sample handling instructions to explicitly endorse saline alongside PBS. (oregon.gov)