Merck Manual

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Using the Comfort Index to Avoid Summertime Heat Stress

Using the Comfort Index to Avoid Summertime Heat Stress

Comfort Index

Situation

Protective Action Needed

Less than 130

Heat stress is not an issue.

None.

130 to 150

Horses will sweat but can stay safe if water intake is adequate.

None, as long as water intake is adequate.

More than 150 (and relative humidity above 75%)

Heat dissipation through sweating may be a problem.

Limit exercise and check horses frequently for signs of stress.

More than 180

Heat dissipation through sweating fails.

Stop all workouts.