Cattle Heat Stroke and Heat Illness: Prevention During Extreme Weather Events

Cattle are vulnerable to heat stress and heat stroke during extreme weather events. As climate change increases the frequency of heat waves, prevention becomes an urgent welfare priority.

Key Facts

Cattle begin experiencing heat stress above the Temperature-Humidity Index (THI) of 72
Signs of heat stress include reduced feed intake, increased respiration rate, drooling, bunching in shade, and reduced production
Heat stroke (core temperature above 41.5°C) causes rapid deterioration and can be fatal
High-production dairy cows generate more metabolic heat and are at greater risk than beef cattle
Shade, ventilation, water access, and feed timing (feeding during cooler parts of the day) reduce heat load
Sprinkler systems providing intermittent wetting followed by fan cooling are among the most effective interventions

Welfare Considerations

Heat stress causes acute suffering that is increasingly common as climate change extends and intensifies hot weather periods. Affected cattle show laboured breathing, excessive salivation, weakness, and behavioural changes reflecting genuine distress. Heat stroke causes organ failure and death in severe cases. The welfare obligation is proactive: providing shade, adequate water (consumption doubles in heat), and cooling before extreme weather events occur rather than responding reactively. For high-production dairy cattle, active cooling infrastructure (fans, sprinklers) is now a welfare essential rather than a production luxury in any climate where summer temperatures regularly exceed 25°C.

What You Can Do

Ensure all cattle have access to shade during hot weather — tree shelter or artificial shade structures
Check and increase water supply capacity before predicted heat events — consumption doubles in heat
Install ventilation and cooling systems in cattle housing in climates experiencing regular hot periods
Avoid cattle handling and transport during peak heat hours — 6-10 AM is the welfare-preferred window
Develop a farm heat emergency plan before summer — include alert thresholds and response protocols