Tolerance Endpoint for Evaluating the Effects of Heat Stress in Dogs
FEDERAL AVIATION ADMINISTRATION WASHINGTON DC OFFICE OF AVIATION MEDICINE
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Animals occasionally die from heat stress encountered during shipment in the nations transportation systems. To provide a basis for a series of studies on shipping crates, environmental conditions, etc., as may be encountered in air transport of dogs, we sought to establish a suitable tolerance endpoint for heathumidity stress in dogs. We monitored the heart rate, respiratorypanting rate, and rectal temperature of 10 male beagle dogs exposed to an air temperature of 95 or - 1 F relative humidity 93 or - 2 percent for less than 24 hours. Of the first six animals, two died during exposure, two died after being removed from the test chamber, and two survived a 24-hour exposure. Based on observations from these six dogs, a rectal temperature of 108 F was tentatively chosen as the tolerance endpoint for subsequent tests. Of four additional animals tested, two were removed from the environmental chamber when their rectal temperature reached 108 F and the two others finished the test with a rectal temperature not exceeding 102.7 F. No ill effects were noted in any of the surviving six animals during a 7-day post-observation period. These and subsequent findings indicate a rectal temperature of 108 F can be safely tolerated and can serve as a tolerance limit for additional studies of heat and humidity effects on dogs.
- Stress Physiology