Equine infectious anemia (EIA) is a viral disease affecting horses globally. Its management through testing programs and the welfare implications of positive diagnosis — including lifelong quarantine or euthanasia — raise significant welfare questions.
The welfare of EIA-positive horses presents a difficult ethical dilemma. Horses diagnosed as carriers but currently asymptomatic face either lifelong quarantine — a severe restriction of social and movement needs — or euthanasia. Neither outcome is welfare-positive for the individual horse. Quarantine preserves life but may impose welfare conditions worse than death for a social animal deprived of conspecific contact indefinitely. Euthanasia prevents suffering from potential future clinical disease but ends a currently healthy animal's life. The welfare calculus depends on the quality of quarantine conditions and the likelihood and severity of future clinical disease. Preventing EIA through rigorous testing programs, clean needle practices, and insect control is the primary welfare-positive intervention, as it avoids placing horses in this impossible situation.