Bovine respiratory disease at weaning and in feedlot entry cattle causes immense suffering and economic loss. Stress-induced immunosuppression at weaning creates vulnerability to respiratory pathogens that rapidly cause painful pneumonia in recently mixed calves.
Weaned calves with BRD experience pleuritic pain, dyspnoea, and high fever — a combination causing significant suffering that, without treatment, progresses to fatal fibrinous pleuritis. Post-weaning stress-induced immunosuppression means multiple animals in a pen often become clinically ill within days of each other, representing a welfare crisis at a management transition point. Welfare-conscious producers implement pre-weaning vaccination, gradual weaning protocols that reduce acute cortisol spikes, delayed transport after weaning to allow immune recovery, and twice-daily clinical scoring at feedlot entry. Early treatment with appropriate antibiotics and anti-inflammatories reduces both suffering and lung lesion severity.