Myxomatosis was deliberately introduced to Australia and Europe to control wild rabbit populations. The welfare consequences for infected rabbits are severe and have prompted debate about intentional disease release as a control method.
Myxomatosis causes a prolonged and distressing death. The disease progresses over 1-2 weeks with increasing debilitation from swollen tissues impeding breathing and vision, dehydration, secondary infections, and acute immune responses throughout. The suffering duration distinguishes myxomatosis from faster-acting control methods. Deliberate introduction of a disease known to cause such prolonged suffering raises profound animal welfare questions about whether ecosystem management goals justify the scale of individual suffering involved. The initial introduction decisions were made before modern animal welfare frameworks existed. Contemporary debates about new biological control releases now routinely include welfare impact assessments as part of the evaluation process.