Leman: Hog trucks, biosecurity in motion
Biosecurity practices vary widely among market hog truck drivers
15 April 2026
4 minute read
By: [Excerpts of two presentations by Lucas Ferreira and colleagues at the University of Minnesota, during the 2025 Leman Swine Conference]
Truck drivers play a critical yet underexamined role in animal transportation. A market hog truck driver may visit the same or multiple farms daily to load pigs and haul them to one or more harvest plants, thereby creating a potential risk for infectious disease transmission to farms.
This study aimed to characterize biosecurity procedures employed by market hog truck drivers. Data were collected biweekly at a Midwestern US harvest facility, interviewing 15 drivers per visit. Drivers were surveyed on personal protective equipment (PPE), trailer sanitation, loads hauled per day, destination after unloading, and documenting whether drivers needed help from plant personnel during unloading.
A total of 123 truck drivers were interviewed between November 2024 and June 2025, totaling 240 surveys, with some drivers being interviewed more than once. Drivers reported hauling one (45%), two (45%), or three (10%) pig loads per day. In 17% of the interviews, drivers confirmed transporting both pigs and cattle using the same trailer. [Editor’s Note: Percentages in this article have been rounded up or down.]
When loading pigs at the farm, 54% of drivers only stepped on the trailer, while 46% stepped on both the trailer and the chute. At the plant, unloading pigs was completed in 19 minutes on average. The use of PPE varied with 92% of the drivers wearing rubber boots, 4% leather boots and 4% wearing other types of footwear. Among them, 8% wore disposable plastic over their footwear and 8% wore shoe covers over their footwear. Fabric coveralls were worn by 58% of the drivers, while 13% used disposable coveralls. The remaining 29% did not wear any type of coverall. Among those who didn’t wear coveralls,19% wore regular clothing (shirt and pants), 5% wore chaps over pants, and 5% wore other garments. Fabric work gloves or latex gloves were used by 86% and 7% of the drivers, respectively. A total of 7% of the drivers used no gloves.
When 97 drivers were asked why they chose their PPE, 14% mentioned biosecurity, while 86% mentioned comfort, avoiding getting dirty or becoming malodourous.
Drivers unloaded pigs without the help of plant personnel in 55% of the cases. However, in 20%, 23%, and 2% of the cases, either 1, 2, or 3 plant employees entered the trailer to assist with unloading, respectively. Non-ambulatory (13%), dead (18%), or both types of pigs (4%) were observed during unloading.
Half (50%) of the drivers had their trailer washed with cold water before loading pigs, 18% did not wash, 15% washed, disinfected, and allowed it to dry, 12% washed and disinfected but did not let the trailer dry, 4% used hot water, and 1% washed, disinfected, and baked the trailer, while less another 1% didn’t know if the trailer was washed.
The results of this study reveal several current risk factors that pose a threat to the industry, including PPE use, trailer sanitation, and farm-level biosecurity breaches.
Trailer contamination
Researchers from the University of Minnesota quantified market hog trailer contamination during unloading and identified the associated risk factors. In this ongoing study, fifteen environmental samples have been collected bi-weekly since calendar week 47 of 2024 at a Midwestern US harvest plant. Samples are collected from the unloading dock and trailers, both before and after unloading pigs, and are RT-PCR tested for porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), and Senecavirus A (SVA). Associated metadata, including trailer origin, sanitation status, destination, and driver or plant employee behavior during unloading are also recorded.
Up to this point in the ongoing study 61% of the samples had at least one of the viruses. PRRSV was detected in 57% of the samples, PEDV in 71% of the samples, PDCoV in 77% of the samples and SVA detected in 32% of the dock samples. Most of the SVA positive samples were detected at the end of 2024 and early 2025.
Before unloading pigs, PRRS (36%), PEDV (33%), PDCoV (45%) and SVA (16%) were detected in the trailers. After unloading, the percentage of contaminated trailers increased for all pathogens. PRRS (50%), PEDV (60%), PDCoV (71%), and SVA (25%), were detected in the trailers.
A total of 64 (27%) out of 240 trailers tested negative upon arrival at the plant. When the dock was contaminated, the odds of the trailer becoming contaminated increased significantly for PRRSV, PEDV, and SVA, but not for PDCoV. A total of 10% of PDCoV-contaminated, 9% of PEDV-contaminated, 6% of PRRSV-contaminated, and 3% of SVA-contaminated trailers went on to load new pigs on a farm without being washed after unloading.
These findings indicate that a significant proportion of trailers arrive at harvest facilities already contaminated, likely due to pathogen shedding by pigs or inadequate sanitation between loads. PEDV and PDCoV contamination was consistently detected throughout the study. These results underscore the urgent need for stringent cleaning and disinfection protocols following unloading.
