Procedures for dead animal removal need to be specific yet adaptable
13 August 2025
3 minute read
Pigs on sow farms often die from various causes, including contagious diseases. An association between using rendering for dead animal disposal and higher risk or porcine reproductive and respiratory syndrome virus (PRRSV) outbreaks has been reported in the literature. However, a detailed characterization of disposal practices and facilities used in the US is needed to understand and mitigate associated risks.
A study by I.A.D. Paploski and colleagues at the University of Minnesota, USA, aimed to characterize the facilities, structures and procedures for dead animal disposal on sow farms, as well as test if environmental samples collected in and around dead animal disposal structures contain detectable quantities of PRRSV and porcine epidemic diarrhea virus (PEDV). The results of the study were presented at the 2024 North American PRRS Symposium.
Ten standard operating procedures (SOPs) from different systems were obtained. Data from SOPs were categorized into sections: biosecurity, dead animal gathering space in the barn, removal from the barn, transport out of the barn, and final destination and used to create a questionnaire for on-site visits. Five farms with 2,000 to 5,000 sows on each from three systems were visited to apply the questionnaire and collect environmental samples for PRRSV and PEDV testing.
The SOPs varied significantly in detail, with the most comprehensive being 12 pages and the shortest having only 1 page containing 11 lines. Biosecurity measures were generally outlined but inconsistent, particularly regarding personnel roles. Dead animal gathering spaces were mentioned in most SOPs, often cleaned and disinfected, but methods varied.
Dead sow removal methods were usually detailed, while dead piglet removal and afterbirth were less consistently addressed. Transport methods of carcasses between the barn and the compost pile or rendering truck pick up site were done primarily using tractors or pickups and were cited in most SOPs, but cleaning protocols were often not mentioned.
Final disposal destinations were inconsistently mentioned. Farm visits revealed that dead animal removal was typically the last task of the day, regardless of PRRS status. Environmental conditions, especially wind direction, can be important if removal happens daily. Wildlife exposure to disposal areas was commonly reported.
Three finisher sites (all PRRSV positive, one PEDV positive) were visited and a total of 25 environmental samples were collected from roads, machines and structures involved in moving dead animals. All samples from one farm tested negative for PRRSV and PEDV by RT-PCR. From the remaining two farms, a total of 12 and 5 samples tested RT-PCR positive for PRRSV-2 and PEDV, respectively. Positive samples were found on dead animals, rendering boxes, skid loader buckets and nearby ground. One PRRSV isolate was obtained from a sample collected on the ground, while no viable PEDV was isolated.
Creating SOPs for dead animal removal on farms is challenging due to the need for specific yet adaptable instructions. SOPs should include detailed biosecurity protocols, procedures for removing dead animals and cleaning and disinfection guidelines.
This study shows that samples collected from or near rendering boxes can test positive for farm-specific viruses and may contain viable viruses. Positive samples on roads suggest potential PRRSV transmission pathways between farms. Further studies on different disposal methods, such as composting or incineration, are warranted to ensure effective biocontainment of viruses on farms.