Post-Weaning Diarrhoea: A Persistent Challenge for Modern Pig Production

Post-weaning diarrhoea (PWD) remains one of the most important health challenges facing the pig industry. It typically occurs within the first 7 to 14 days after weaning, when piglets face overwhelming nutritional, microbiological, social and environmental stressors and changes. Studies consistently identify enterotoxigenic Escherichia coli (ETEC), particularly F4 and F18 strains, as the primary infectious cause of PWD, although rotavirus, management failures, dietary factors and poor gut development also contribute significantly.

More specifically, F4 and F18 ETEC are responsible for approximately half of diagnosed PWD outbreaks, making them the dominant bacterial pathogens in commercial systems with an increasing role for rotavirus and multifactorial enteric disorders, highlighting the complex nature of modern PWD.

The economic impact is substantial due to increased mortality, a reduced growth rate, poorer feed efficiency, increased medication costs, and additional labour. For a 1,000-piglet group, an additional 5% mortality represents the loss of 50 piglets. At a weaned piglet value of €40-60, this alone corresponds to €2,000-3,000 in direct losses, excluding downstream impacts on finishing performance, increased medication or veterinary costs.

As important as economics, PWD is a significant animal welfare issue when an industry is under intense scrutiny. Affected piglets experience dehydration, anorexia, intestinal inflammation, discomfort and impaired growth. Severe cases may require euthanasia, while surviving pigs often show lifelong reduced performance.

PWD is also closely linked to antibiotic use in pig production. Historically, oral antimicrobials such as colistin, tetracyclines and penicillins were widely used to control outbreaks. Several reviews have identified the post-weaning period as one of the highest antibiotic-use phases in pig production. However, increasing concerns regarding antimicrobial resistance and EU antimicrobial-reduction targets have intensified efforts to prevent PWD through nutrition, vaccination, management improvements and gut-health interventions rather than routine antibiotic treatment.

Post-weaning diarrhoea is far more than a digestive disorder; it is a multifactorial problem with significant impact on profitability, welfare, and antibiotic usage. As producers face increasing pressure to reduce antimicrobial dependence while maintaining performance, the focus must shift toward sustainable preventive approaches. Understanding the key drivers of PWD is the first step. The next is implementing targeted nutritional and management solutions that help piglets navigate the post-weaning transition successfully.

Eriksen, E.Ø., Kudirkiene, E., Christensen, A.E., Agerlin, M.V., Weber, N.R., Nødtvedt, A., Nielsen, J.P., Hartmann, K.T., Skade, L., Larsen, L.E., Pankoke, K., Olsen, J.E., Jensen, H.E., & Pedersen, K.S. (2021). Post-weaning diarrhea in pigs weaned without medicinal zinc: Risk factors, pathogen dynamics, and association to growth rate. Porcine Health Management, 7, 54. https://doi.org/10.1186/s40813-021-00232-z

Lekagul, A., Tangcharoensathien, V., & Yeung, S. (2019). Patterns of antibiotic use in global pig production: A systematic review. Veterinary and Animal Science, 7, 100058. https://doi.org/10.1016/j.vas.2019.100058

Luppi, A., Gibellini, M., Gin, T., Vangroenweghe, F., Vandenbroucke, V., Bauerfeind, R., Bonilauri, P., Labarque, G., & Hidalgo, Á. (2016). Prevalence of virulence factors in enterotoxigenic Escherichia coli isolated from pigs with post-weaning diarrhoea in Europe. Porcine Health Management, 2, 20. https://doi.org/10.1186/s40813-016-0039-9

Rhouma, M., Fairbrother, J.M., Beaudry, F., & Letellier, A. (2017). Post-weaning diarrhea in pigs: Risk factors and non-colistin-based control strategies. Acta Veterinaria Scandinavica, 59, 31. https://doi.org/10.1186/s13028-017-0299-7

Guardabassi, L., Pedersen, K., Nielsen, J.P., Thymann, T., Nagl, V., Good, L., Gonzalez-Zorn, B., Middelkoop, A., Molist, F., Jansman, A.J.M., et al. (2026). Prevention of post-weaning diarrhoea in intensive pig production: Insights from the European Union project AVANT. Scientific and Technical Review of the World Organisation for Animal Health (WOAH), 44. https://doi.org/10.20506/rst.44.37