Transport-related pig mortality: Synergistic effects of travel distance and season

This study aimed to assess the potential synergistic effect of season and transport distance on mortality rates in pigs transported to slaughterhouses in the Czech Republic between 2017 and 2023. A retrospective analysis was conducted using data from all pig transports under official veterinary supervision during the monitored period. Transport-related mortality was evaluated in sows (n = 348 141), piglets (n = 97 785), and finishing pigs (n = 15 821 391). Mortality was significantly influenced by both season and transport distance in all pig categories ( P < 0.05). The highest mortality rates occurred during summer, with the most unfavourable combination being summer and very long transport distances (> 300 km) in sows (1.34%) and finishing pigs (0.51%). In piglets, the most critical combinations were summer with long distances (101–200 km: 1.52%; 51–100 km: 1.05%). Mortality was consistently lowest in winter and at short transport distances (≤ 50 km). These findings confirm a synergistic effect of heat stress and transport duration on pig mortality. This large-scale national dataset highlights the need for species- and category-specific transport guidelines, particularly during hot weather and longer journeys. Reducing journey length during summer and improving transport conditions are essential to improve animal welfare and reduce economic losses.