Leptospirosis in cattle causes reproductive failure, milk drop syndrome, and haemolytic anaemia — creating welfare harm in individual animals while presenting a significant zoonotic risk to farm workers.
Leptospirosis causes welfare harm at both the individual and herd level. Acute haemolytic disease in individual cattle — caused by serovars like Pomona — produces fever, rapid red blood cell destruction, and the visible distress of haemoglobinuria, jaundice, and weakness. The chronic reproductive consequences of Hardjo infection — abortion storms, stillbirths, weak calves — cause acute welfare harm to both dams and their offspring at the moment of pregnancy loss, while sustained reproductive failure erodes herd productivity and increases the pressure for early culling. The welfare impact of leptospirosis extends to farm workers who risk serious illness through occupational exposure. Vaccination programmes that reduce both reproductive disease and environmental shedding represent the most impactful combined welfare and zoonosis control measure available. Prompt diagnosis and antibiotic treatment of clinical cases reduces individual animal suffering.