Border disease virus causes reproductive failure and congenital abnormalities in sheep, with significant welfare implications for affected lambs and ewes.
Border disease creates welfare harms at multiple stages. Ewes experiencing abortion and stillbirth undergo reproductive loss and the associated physiological stress. Hairy shaker lambs are born with permanent neurological deficits — tremors, coordination failure, and growth failure — and most die or require euthanasia within weeks. Their suffering in this period is significant. Persistently infected lambs appear outwardly normal initially but have severely compromised immune systems, making them susceptible to secondary infections throughout their short, miserable lives. The welfare cost of uncontrolled border disease in a flock is substantial. Detection of PI animals through blood testing and their removal is the most impactful welfare intervention.