It’s summer, and it’s hot. So hot, in fact, that some states have seen all-time record highs already this summer. My dog and I are enjoying the air conditioning at the moment, staying out of the blazing sun until the cool evening hours. Our animals, however, can’t always avoid the sweltering heat.
Hyperthermia is the term for abnormal elevation of body temperature due to the inability of the body to dissipate enough heat. Not to be confused with fever, hyperthermia happens when the environment is hot and the animal’s normal heat-loss mechanisms are overwhelmed.
Evaporation is a great way to dissipate heat. In the same way that being sprayed with a hose helps cool you off, the loss of heated moisture from the skin does the same. Panting is a major way of heat dissipation used by dogs, cats and even cattle. Dogs pant fairly regularly, but by the time you see a cat or cow panting they are in serious distress. Sweat is also evaporative and is the major mode of heat loss employed by horses. Dogs and cats do sweat through glands on the pads of their paws, but they don’t really use that for heat loss. Evaporation occurs more slowly when the air is humid, so the efficiency of panting and sweating for heat loss drops on oppressive, muggy days.
Conduction is the most efficient means of heat transfer. A cool surface is a very effective way to cool the body. Conversely, having to lay on a hot floor or ground can rapidly increase body temperature. For large animals, wading belly deep into cool water can help to dissipate large amounts of thermal energy and keep an animal from overheating. Sprinklers can cool large areas of ground for livestock to lay on in extreme temperature. Even just spreading straw can be better than laying on heated, dark earth for livestock.
Most people think shaving their animals in the summer will keep them cool. The reverse is true. A wooly coated sheep is a great example. Sheep actually use that layer of wool to keep cool, and sheared animals are most at risk for heat stress in extreme temperatures. While most of us think of wool as the sheep’s warm winter coat, it serves double duty in protecting them from the sun. The thick wool traps the cooler air near the skin and the wool fibers dissipate heat more rapidly. A dog’s coat is protective in the same way, and most dogs do not benefit from shaving. Some of the very heavy coated and arctic breeds may benefit from shaving, especially if they aren’t well-groomed or have matted coats.
The best way to cool an overheated pet isn’t to throw them in ice water or give them an alcohol bath. The body’s response to rapid exposure to cold is to shift blood flow away from the extremities. The result is that the overheated blood is concentrated into the sensitive internal organs and the brain. In a severely hyperthermic animal this can be extremely damaging. Cool animals by placing cool, wet towels on the neck, ears or armpits. Continue to change the towels as they warm.
Exercise in the heat can rapidly lead to hyperthermia. Try to keep exercise and stress to a minimum during high temperatures, and plan events for cooler times of day. Moving livestock in the morning before the high temperatures come can mean the difference between healthy animals and severely heat stressed animals. Make sure heat stressed and exercised animals have access to fresh, clean water since the water intake requirement increases substantially as animals use evaporation to cool.
We can’t avoid the summer heat, but we can work around it. Understanding how animals shed heat is important to preventing hyperthermia, as is planning ahead to make sure activity during extreme temperatures is minimized. Remember the water, exercise in the morning, and keep a cool spot available.
This blog was written by Neogen’s professional services veterinarian, Dr. Joe Lyman. For more information on Neogen’s animal safety division, click here.