Testing of umbilical cords by real time PCR is suitable for assessing vertical transmission of porcine reproductive and respiratory syndrome virus under field conditions.

The objective of this study was to test the suitability of umbilical cord (UC) sampling and ear vein swabbing (EVS) as alternatives to jugular vein bleeding (JVB) for the assessment of vertical transmission of porcine reproductive and respiratory syndrome virus (PRRSV). Twelve farms suspected to be PRRSV-positive unstable were selected and the three types of samples were obtained from 21 batches of newborn piglets (n=387). The proportions of positive results, viral loads and time spent to collect the samples were compared. UC yielded the highest detection rate, with 76 positives compared to 55 JVB- and 45 EV-positive results (P<0.05). Average Ct values were 26.6±8.5 for JVB, 30.8±6.4 for EV and 32.1±4.85 for UC (P<0.01). UC was the fastest collection method (mean 24s vs. 55s for EV and 72s for JVB; P<0.05). In this study, UC testing was a faster and more sensitive alternative to JVB or EV for the detection of PRRSV in newborn piglets.