Study tests saline as transport medium for T. foetus PCR

A new noninferiority trial suggests that 0.9% sterile saline may be a practical alternative to phosphate-buffered saline, or PBS, for transporting bovine preputial washing samples for Tritrichomonas foetus direct RT-rtPCR testing. In the study, published in the Journal of Veterinary Diagnostic Investigation and previously presented at the 2025 Conference of Research Workers in Animal Diseases, researchers from Mississippi State University and the Nebraska Veterinary Diagnostic Center compared 1,200 samples prepared from weekly preputial washings of known negative bulls and inoculated at the assay’s reported limit of detection. Sensitivity was 70.7% for PBS and 73.3% for saline, while specificity was 99.7% for PBS and 100% for saline. The study found no statistically significant difference between media, although formal noninferiority for sensitivity was inconclusive at the prespecified margin. (crwad.org)

Why it matters: For veterinary professionals, the finding addresses a practical bottleneck: many field veterinarians don’t routinely stock PBS, while sterile saline is widely available. That could make sample collection simpler in practice if laboratories and regulators accept saline for direct RT-rtPCR workflows. The broader testing landscape is already moving in that direction in some jurisdictions. Nevada’s animal disease lab has accepted PBS or saline for direct T. foetus RT-rtPCR since February 5, 2024, and Oregon now accepts PBS for official PCR testing, reflecting a wider shift away from culture-dependent handling as RNA-based assays targeting the 5.8S rRNA improve sensitivity and turnaround time. (agri.nv.gov)

What to watch: Watch for whether more state labs and cattle health regulators explicitly add saline to approved collection guidance for official T. foetus RT-rtPCR testing. (agri.nv.gov)