An exploratory study to characterize current oral fluid usage in pig production systems in the United States

MSHMP researchers Xiaomei Yue, Mariana Kikuti, Marcello Melini, Sarah Vadnais, and Cesar A. Corzo share the results of their pilot study characterizing the current use of oral fluid sampling in US pig production systems.

Key points:

  • 66 out of 67 respondents from 42 companies and clinics are familiar with or actively use oral fluid sampling for diagnostics.
  • A total of 35%, 27% and 3% of the respondents collected oral fluids on a monthly, weekly and daily basis, respectively.
  • Most (69%) respondents use one rope for every two pens while the median number of ropes per barn was 3.


Oral fluid (OF) sampling has been widely used in the United States (U.S.) swine industry for at least a decade. This sample type has been rapidly adopted by the industry for endemic disease monitoring as it readily optimizes time and resources when conducting population-based-like sampling. We conducted a pilot study with the aim to characterize the current use of OF sampling in pig production systems in the U.S. swine industry.


Two online questionnaires were employed in two research phases: one targeting field personnel within production systems and another focusing on swine veterinarians. The questionnaires gathered data on the implementation and primary use of OF, sampling protocols, and sample handling and processing procedures. A convenient sample of production systems was invited to participate, and practitioners were invited through individual email invitation and the AASV newsletter. The questionnaire capture data between June and October 2023. The collected survey data were cleaned and analyzed using descriptive statistics.


We received in total of 67 valid responses from production systems and veterinarians from 42 companies and clinics. Among the 67 respondents, 91% were veterinarians and 9% were field personnel/farm supervisors. Based on survey responses, we believe that the acquired data accounts for 58M growing pigs and 3.9M sows; however, we believe the studied population might be overestimated due to overlapping between company and clinic responses. The findings demonstrated widespread familiarity and adoption of OF sampling in the industry, with 99% (66 out of 67) of respondents reporting its use for diagnostics or surveillance. Primary usage included routine surveillance (62%) and diagnosing clinical cases (33%).

When hanging the rope, 69% of the respondents reported using one rope for every two pens, 21% use one rope per pen, while the remaining respondents employ alternative approaches, such as using three ropes per barn, two ropes per barn, or making determinations based on airspace/rooms. The OF sample size reported was summarized in Table 1. The median number of ropes per barn was 3. The median number of pens sampled per barn was 6; and median number of pigs that are considered to have chewed a single oral fluid-rope sample was 150, which is related to pooling multiple rope strands in some responses. The median time the pigs have access to the rope was 20 minutes (Min; Max: 7.5; 60; Interquartile range: 17.5; 30).

The sampling frequency for routine surveillance is monthly for 35% of the respondents, weekly in 27% cases, and daily in 3% cases. We specifically looked at the responses reporting routine surveillance, compared to their sampling frequency when there are clinical signs on the site (Figure 1). Figure 1 shows that the sampling frequency increased in 64% of cases (i.e., changed from monthly to weekly/daily or from weekly to daily when clinical signs were present); in 23% of cases, the OF sampling frequency stayed the same regardless of clinical signs present whereas in 13% of the respondent decided to decrease the frequency or just sample once when clinical signs arise. Most respondents reported having written protocols for sample handling, with 50% making these protocols available to farm personnel.


This study offers a comprehensive overview of OF usage in U.S. pig production systems. It underscores the need for standardization in collection methods to further advance the utilization of OF sampling in veterinary practice. The information provided in this study reflects the OF sample management and its role in surveillance, which will substantially push forward the standardization of OF collection and handling, aid in the early detection of emerging pathogens, and improve swine health monitoring.

Authors would like to acknowledge Dr. Pam Zaabel for her study input and the National Pork Board – Grant 23-043 for funding this project.