While mules are less susceptible to heat related problems, they are not immune. A mule kept in a poorly ventilated area such as a trailer becomes a likely candidate for heat stroke. Standing in a hot trailer, no breeze, unable to move about, the mule is at risk. A poorly ventilated stall or barn can be just as dangerous. Ad to both these situations the likelihood the mule is being exhibited at a show.
Additional stress is put on the animal to perform in a less than comfortable situation.
There are fewer opportunities for the mule to drink during a performance or he may be off his water because it tastes different. All these factors may lead to a mule who succumbs to heat stroke. In addition, high humidity intensifies the probability that the animal's cooling system may be impaired. Especially in traveling from a dry area of the country to one that has higher humidity, a mule may not get a chance to acclimate itself to the humidity before performance demands are put on it. The higher humidity makes it more difficult for the mule's cooling system to get rid of the excess heat that has been generated by increased activity in temperatures above 80 degrees and relative humidity above 50 percent.