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| Over heating is sporadically
encountered in cattle, but is really a rare problem. High humidity
contributes to the likelihood of heat stroke or prostration because water
evaporation from the oral and nasal cavities is decreased, in spite of
rapid panting. At an environmental temperature of about 88 degrees,
heat dissipation mechanisms such as sweating and evaporative cooling must
take place to prevent a rise in body temperature. Sweat gland activity
in cattle increases as the temperature goes above the thermoneutral zone.
Panting is an important heat regulatory device in cattle. Panting
often occurs at rectal temperatures at or above 104 degrees F, but may
begin even at lower body temperatures.
The signs of overheating may develop suddenly and depend upon the environmental conditions and the health of the cattle exposed to the heat. Some animals manifest restlessness, excitement, and spasms of certain muscles. However, other animals may be dull and depressed. A protruding tongue may be covered with saliva, and frothy mucus discharged at the nostrils. Rectal temperatures of overheated cattle have ranged as high as 107 to 115 degrees F. Overheating in cattle can be prevented
under most management conditions. Allowing animals access to cool
water and mineral supplements is a must in very hot summer weather.
Shade and free air circulation should be provided if at all possible.
Avoid working cattle during very hot parts of the day. Very excitable
cattle will be even more prone to heat stress if handled at high environmental
temperatures. If animals are going to have limited access to water
under stressful conditions such as shipping by truck or trailer, they should
be allowed water prior to further stressful situations.
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