The paper develops the concept of rewilding epidemiologies to examine how large herbivores introduced for their ecological engineering simultaneously re-engineer epidemiological landscapes. Drawing on ethnographic research with feral wild boar and free-roaming rewilding pigs in the UK, it shows how these animals and their disease ecologies unsettle biosecurity governance, generating political and epistemic frictions. The paper concludes by calling for forms of animal health governance that move beyond exclusion and eradication toward managing multispecies coexistence.