Working in Extremely Hot Weather

by Robert Milner, July 2015  

From the standpoint of evolution, dogs have survived extreme weather quite well over thousands of years. However the last 200 years have brought a change in breeding selection. Man has replaced Mother Nature in the breeding selection process. Increasingly we have been selectively breeding retrievers to build their drive. One effect of this selective breeding has been the decrease or elimination of the "off switch" in many retrievers. Today many retrievers will keep going even though it may kill them. It is the responsibility of today's retriever owner to learn how to act as a governor on some of the dogs activities, in order to keep him safe. To the dog the most dangerous environment is heat.

Every dove season in the south a number of dogs die from heat stroke. Those deaths are easy to prevent. Hunters traditionally get wrapped up in learning and recognizing the symptoms of heat exhaustion and trying to manage the problem after the symptoms appear. That is a high risk strategy. If you wait until the symptoms appear, the dog probably has about a 50% probability of dying. Manage the heat and keep the symptoms from appearing. That is the safest strategy for your dog. Basically it boils down to rationing his strenuous exercise and keeping him wet or damp on the outside when he is working in high temperature conditions. Since muscle movement is the producer of heat in a dog, managing heat levels means managing exercise levels.  

A dog's normal body temperature is 101 degrees Fahrenheit to 102.5 degrees Fahrenheit. Strenuous exercise will spike that body temperature up to the range of 106 degrees to 108 degrees. The dog's body cannot withstand that high a temperature for extended periods. He will go into irreversible heat stroke and die. He has to lose some of that body heat fairly quickly. If it is 95 degrees and you have 3 doves downed in a soybean field and the dog has just hunted vigorously for five minutes before returning with first one, don't immediately send him for number 2. Sit him down in the shade for 10 or 15 minutes and let him lose some heat. Then send him for the next downed bird. Moderating his activity levels will keep his body heat at manageable levels.

Your second major tool for helping your dog fight heat is evaporation. Evaporation literally sucks heat out of the air in the vicinity of a wet surface. That is why you feel cool when you walk into a forest. As part of their metabolic cycle trees evaporate water off of their leaves. A single tree evaporates hundreds of gallons of water per day. A building benefitting from the active evaporative cooling of trees will experience a 17% reduction in cooling requirement. Just think of the benefit of a 17% reduction in heat to a dog on a hot day.

When water evaporates and goes from the liquid to the gaseous state. The process absorbs energy in the form of heat. When you step out of the shower and feel chilled, that is evaporation working. Evaporation can lower the temperature in the immediate surrounding area five to ten degrees. Evaporation is also proportionate to the surface area that is wet. Unlike people, dogs do not sweat. With a dry dog, evaporation is limited mainly to the surface area of the mucous membranes of his nose, mouth and throat. With a dog that is wet over his entire body, the surface area of evaporation is increased hugely, and the dog will much more readily lose heat.

When you are hunting in hot weather, a good practice is to start with the dog wet and keep him damp if possible. That way you start with him cool and help him to stay cool from evaporation.     

Several cautions are in order for wet dogs and heat.     

1. Don't put a wet dog in an enclosed space like a dog crate. The lack of air circulation will severely curtail evaporation and allow heat build up.
2. Before counting on a small pond to cool your dog, stick your finger in the water. If it feels warm, then immersion is not going to cool the dog. Put him in for a moment to wet him down, then bring him out for evaporative cooling to go to work