Heat stress is a significant issue for pets and livestock.
With the arrival of summer, the heat and humidity combine to boost the "heat index." The heat index is used to describe how hot it feels.
The heat index, like the cold weather "chill factor," applies primarily to warm-blooded animals. Humans, pets and livestock both generate significant amounts of body heat. In cold weather, much of that heat is used to maintain body temperature. Heat always tends to move from warmer objects to cooler objects. When the surrounding air is below body temperature, disposal of excess body heat is relatively easy. In hot weather, when the air and nearby objects are near or above body temperature, the disposal of excess body heat becomes more difficult.
One of the most important things that livestock producers and pet owners can do in hot weather is to provide an ample supply of cool, clean drinking water. Animals should have access to shade. It is also helpful to arrange for the water to be in the shade. A container of water in the shade will be at, or slightly below, air temperature. A pan, bucket or tank of water that sits in the sun for much of the day will be dramatically hotter than the air, and may very well be too hot to drink.