Johne's disease is a chronic, progressive condition causing weight loss and diarrhoea in sheep and cattle, with long incubation periods making control challenging.
Johne's disease causes prolonged suffering in affected animals. The progression from subclinical infection to clinical disease involves worsening emaciation, diarrhoea, and weakness over weeks to months. Animals that develop clinical disease cannot be cured and face inevitable deterioration. The welfare response requires clear decision criteria for when euthanasia is more welfare-positive than continued management of a chronically ill animal. Prevention through vaccination and biosecurity is far preferable.