Bovine respiratory disease in dairy calves in the first months of life causes significant welfare harm, affects long-term health and productivity, and represents one of the most important welfare challenges in the dairy industry.
Dairy calves with BRD experience significant welfare compromise from respiratory illness. Fever, reduced appetite, breathing difficulty, and depression cause acute suffering. The early housing period when calves are most susceptible to BRD overlaps with the immunological gap after maternal antibody decline, creating a window of vulnerability. Calves that recover from clinical BRD may have residual lung damage that causes chronic respiratory compromise and reduced physical capacity throughout their productive life. The difficulty of detecting illness early in calves that mask signs means many animals suffer for longer before treatment begins. Housing conditions including ventilation, humidity, and stocking density are primary risk factors within producers' control.