Keeping your Dog Cool while Participating in Summer Sports
by Morganne Wagoner-Perry

Heat is one of the most severe environmental stresses a dog can be subjected to. Major changes in body fluids and tissues associated with over heating is known as Hyperthermia. In all mammals, several complex mechanisms exist that are designed to keep the internal (core) body temperature within a narrow acceptable range. In dogs, the normal core temperature is within 100.5 – 102.0 degrees Fahrenheit. The thermoregulatory center, located in the region of the brain (called the hypothalamus), is responsible for activating the appropriate physiological mechanisms to raise or lower the body temperature back into the normal range. For example, a dog’s panting and lying down are physiological reactions to excessive heat. When working a dog in the heat keep in mind that when muscles get too warm, they function less efficiently.  When a dog's body warms too much, its non-muscular body functions not only work less efficiently, but actually may fail entirely, thus presenting a life-threatening situation to the dog.
 

Dogs are pretty adaptable and can become acclimated to working in many different environments. So in a dog who is accustomed to heavy work in a hot climate, the thermoregulatory center is set to a higher temperature than that of a dog who is worked in cooler weather (or spends his days lounging around in an air-conditioned house). A dog living in an environment of constant air conditioning will be more susceptible to heat stroke from prolonged exposure to extreme heat and humidity than a dog that has been acclimatized to the heat. This acclimation process does take some time (3 weeks or more). So if you plan to work your dog in an event outside in hot weather, it’s very important to begin training in the heat several weeks ahead in order to acclimate your dog.

The canine has four basic mechanisms for heat loss (cooling). Evaporation, conduction, radiation, and convection. Evaporation being the most efficient. Since dogs only have a few sweat glands (located on the pads of their feet), evaporative cooling occurs mostly through evaporation of saliva and secretions from oral and respiratory membranes during panting. Unfortunately, since panting is an active physical process that requires energy to perform, by itself, it is not always the most effective way to cool a dog who is exercising in the heat. Also this evaporation is minimized with increased relative humidity or poor ventilation. Stagnant air near the body is quickly elevated to body temperature  rendering useless the most important means of heat elimination in the dog’s body.

Because dogs are covered with a hairy coat, conduction is not really an efficient way to cool and the effectiveness of heat loss through radiation is dependent on several factors: A heavy-coated dog may radiate very little heat however, he may also gain little heat as well because of the protection of a heavy coat. A tall lanky dog will generate more heat loss than a short-legged, stocky dog.

Convection is heat loss through conduction to moving air currents. Without air movement, conduction of heat from the body ceases and the air near the body approaches the surface temperature. Using a fan to move the air helps as the hot air next to the body is constantly being replaced by cooler air.  Because of their coat, dogs are less efficient with heat loss through convection alone. So a combination of evaporation and convection will facilitate the most efficient means for heat loss in your canine athlete.

Factors that put dogs at further risk for overheating:

• High humidity
• Lack of acclimation to hot weather
• Obesity and poor conditioning
• Individual body conformation and coat (short, stocky, heavy-coated dogs vs. lean, leggy, short-coated dogs)
• Temperament (dogs who stress or get hyped-up at events may overheat more quickly than a dog who can rest calmly in his crate).

 
A dog suffering from heatstroke will display several signs:

• Rapid panting
• Bright red tongue
• Red or pale gums
• Thick, sticky saliva
• Depression
• Weakness
• Dizziness
• Vomiting – sometime with blood
• Diarrhea
• Shock
• Coma
   

If you suspect a dog may be experiencing heatstroke, remove him from the hot area immediately. Prior to taking him to your veterinarian, lower his temperature by wetting him thoroughly with cool water (for very small dogs, use lukewarm water), then increase air movement around him with a fan. CAUTION: Using very cold water can actually be counterproductive. Cooling too quickly and especially allowing his body temperature to become too low can cause other life-threatening medical conditions. The rectal temperature should be checked every 5 minutes. Once the body temperature is 103ºF, the cooling measures should be stopped and the dog should be dried thoroughly and covered so he does not continue to lose heat. Even if the dog appears to have recovered before you reach the veterinarian, he should still be examined. He may be dehydrated or have other complications.
 

To keep your dog from overheating:

• Compete with only fit, well-conditioned and well-acclimated dogs.
• Provide plenty of shade
• Plenty of air circulation (portable fans) and avoid using mesh or plastic crates which restrict air-flow. Wire crates or x-pens are ideal for optimal air circulation.
• Keep your dog well-hydrated. Keep track of how much water she is drinking. Since dogs don’t sweat, electrolyte replacement solutions are not needed. Stick to plain cool water.
• For maximum external cooling, wet your dog in a pool or with a hose/sprayer paying special attention to the groin area, throat, and armpits.
• Cool coats can help. Heat from the body evaporates the water in the coat, thus cooling the dog.
• Feeding your dog four or more hours prior to the time of activity ensures that blood flow is not diverted inward to the gastrointestinal tract. (However, small high-carb snacks fed at intervals during activity may help maintain muscle energy stores).

Remember, a combination of wetting your dog and using a fan is the most efficient means for keeping your dog cool (evaporation and convection) as well as providing a well-ventilated environment.

Resources:

Duder, Claire D.V.M. (2006). Thermoregulation for Dummies: How to Help Your Dog Stay Cool When the Weather Isn’t. Clean Run 12(6) 47-51.

Downey, Robert L. (1981). Heat Stress in Dogs. Retrieved June 15, 2006.

Web Site: www.webheads.co.uk/sleddog/ezine/pdf/Heat_Stress.pdf

Search Dogs Northeast: Canine Search and Rescue Team. Reference Library.

Web Site: http://www.searchdogsne.org