Specimens collected from dead pigs are a welfare-friendly and cost-effective active surveillance. This study aimed to evaluate the accuracy of different postmortem specimens from dead piglets for disease detection, using PRRSV as an example. Three farrow-to-wean farms undergoing PRRSV elimination were conveniently selected. Samples were collected at approximately 8- and 20-weeks post-outbreak. Postmortem specimens included nasal (NS), oral (OS), and rectal (RS) swabs, tongue-tip fluids (TTF), superficial inguinal lymph nodes (SIL), and intracardiac blood. These were tested individually for PRRSV by RT-PCR. Sensitivity, specificity, negative and positive predictive values, and agreement of postmortem specimens were calculated using intracardiac sera as the gold standard. OS and SIL had the best overall performance, with sensitivities of 94.6–100%, specificities of 83.9–85.1%, and negative predictive values of 97.3–100%. TTF had high sensitivity (92.2%) but low specificity (53.9%) and positive predictive value (48.3%). While challenges in meeting sampling targets due to variable pre-weaning mortality were noted, PRRS was detected in all postmortem specimens. OS and NS showed promising results for disease monitoring, though TTF, despite their sensitivity, had lower specificity, making them less suitable for individual infection assessment but useful for assessing environmental contamination.

Background: Hesitation on eliminating Porcine Reproductive and Respiratory Syndrome virus (PRRSV) from breeding herds exists since it is difficult to predict how long the herd will remain virus-free. We aimed to estimate the time that breeding herds remained virus-free (naïve) after PRRSV elimination was achieved. Methods: Production systems voluntarily shared their breeding herds’ health status weekly between July 2009 and October 2021. PRRSV incidence rate and the total number of days a breeding herd remained virus-free were estimated. Results: A total of 221 (17%) herds reached the naïve status 273 times. The median time sites remained in this status was approximately two years. The overall PRRS incidence rate after sites achieved a naïve status was 23.43 PRRS outbreaks per 100 farm years. Conclusion: Estimates obtained here provide insights on how frequently and for how long sites remain naïve, which contribute to informing management practices for PRRS control.

Senecavirus A (SVA) is an endemic pathogen with ongoing relevance to the U.S. swine industry due to its clinical resemblance to foot-and-mouth disease (FMD) and its potential impact on animal health and trade. This study analyzes the incidence and geographic distribution of SVA outbreaks in U.S. breeding herds from January 2015 to December 2024. We used enhanced surveillance by combining diagnostic data from veterinary diagnostic laboratories and practitioners’ reports to assess SVA incidence, identifying temporal fluctuations and regional patterns. Our findings indicate that the cumulative incidence of SVA in U.S. breeding herds is low overall (<2.5% per year), with peak incidence observed during the third and fourth quarters of the calendar year. Outbreaks are more frequently reported in the Midwest. Our results suggest potential seasonality or regional factors influencing disease transmission. The median time interval between SVA outbreaks for sites experiencing more than one outbreak is 402 days. This study provides valuable insights into the current epidemiology of SVA in U.S. breeding herds, and highlights the need for continued monitoring and preparedness to prevent future outbreaks.

Assessing whether post mortem samples can provide value for monitoring during the post-weaning stages is necessary as this methodology can be adopted by the industry when resources are scarce. The objectives of this study are to assess pathogen detection in tongue tip fluids (TTFs), oronasal swabs (ONSs), rectal swabs (RSs), and superficial inguinal lymph nodes (SILNs). Two farms (one wean-to-finish farm and one finishing farm) undergoing a porcine reproductive and respiratory syndrome virus (PRRSV) outbreak were included, and 30 dead pigs were sampled during each farm visit. For PRRSV, the diagnostic accuracy of TTF, ONS, RS, and SILN were calculated using intracardiac serum as the gold standard. We also characterized the detection of PCV-2, PCV-3, PPV-1, PPV-2, Lawsonia intracellularis, and IAV in all collected specimens. Overall, TTF and SILN had the highest sensitivity for PRRSV-2 detection (95% and 99%, respectively). Most other pathogens were detected in TTF, with the highest detection rates were for PPV-2 (99%) and PCV-2 (41%). RS had mostly good detection rates for PPV-2 (27–73%), while ONS had similar detection rates (37%) to TTF (38%) for IAV. Altogether, this indicates that post mortem specimens can provide value for pathogen detection.

Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant challenge, costing annually approximately USD 1.2 billion to the U.S. swine industry due to production losses associated with, but not limited to, reproductive failure, abortion, and high pre-weaning mortality among piglets. PRRSV is endemic, with thirty percent of the U.S. breeding herd experiencing outbreaks annually. The shedding status of animals on a farm is typically assessed using serum or processing fluids from piglets, but tongue tips from deceased animals are emerging as a potential alternative specimen to support farm stability assessment. This study explored the impact of various processing and testing strategies on tongue tips to enhance the sensitivity and specificity of PRRSV detection in sow herds. We collected tongue tips from 20 dead piglets across seven sow farms, testing different pooling strategies (individual testing, and pools of n = 5 or n = 20) and laboratory processing methods (tongue tip fluid—TTF, versus tongue tissue homogenate—TTH). Additionally, we simulated storage and shipping conditions, comparing frozen samples to refrigerated ones tested at intervals of 1, 4, and 7 days post collection. RT-PCR testing revealed higher sensitivity and lower cycle threshold (Ct) values for TTF compared to TTH, suggesting that tongue tips are better tested as TTF rather than TTH for PRRSV detection. Pooling samples reduced diagnostic accuracy. Frozen samples had lower absolute Ct values, and Ct values increased by 0.2 Ct values each day post collection when the sample was kept refrigerated, emphasizing the importance of minimizing shipping delays. Tongue tips are a practical, easy-to-collect specimen that target potentially infected animals (dead piglets), offering valuable insights into swine herd health, but sample processing approaches significantly influence diagnostic outcomes. If tongue tips are used by veterinarians to assess viral presence on a farm, testing the TTF instead of TTH should be prioritized. Storage and shipment conditions should be considered to optimize laboratory results.

Oral fluid sampling has been widely adopted in swine health surveillance, offering an effective and cost-effective method for monitoring endemic and emerging diseases. This study characterized oral fluid sampling practices within U.S. pig production systems. An online questionnaire was conducted between June and October 2023, targeting swine practitioners, to collect data on implementation, usage, sampling protocols, and handling procedures. A total of 67 valid responses were received, representing an estimated 58M growing pigs and 3.9M sows. Nearly all respondents (99%) reported being familiar with or using oral fluid sampling for diagnostic purposes. The median of ropes hung per barn was two (interquartile range [IQR]: 1; 4), with 68% using one rope per two pens. The median of pens sampled per barn was six (IQR: 4; 10). Pigs typically accessed the rope for a median of 20 min (IQR: 17.5; 30). Sampling frequency varied by farm types. Half of gilt-development-unit (GDU) respondents collected samples monthly. When submitting samples to the veterinary diagnostic laboratories, pig age (91%) was the most frequently included information. This study reveals the widespread and varied adoption of oral fluid sampling, highlighting the need for standardized collection procedures to support consistent interpretation and improve reliability for detecting emerging pathogens.