Heat stress is one of the most significant welfare and productivity challenges facing cattle globally, costing the US livestock industry an estimated $2.4 billion annually and causing measurable suffering across millions of animals.
Heat stress causes acute suffering in cattle, manifesting as panting, bunching in shade, reduced activity, and cessation of rumination. Chronically heat-stressed animals show elevated cortisol, suppressed immune function, altered gut microbiome, and increased susceptibility to respiratory disease. High-producing dairy cows are especially vulnerable because metabolic heat production increases with milk yield. Welfare assessment during hot periods should include respiration rate scoring, shade-seeking behaviour, and water intake monitoring. Effective interventions include provision of shade, forced ventilation and evaporative cooling in barns, access to clean water at multiple points, and adjusted feeding schedules to reduce metabolic heat load during peak temperatures.