Special consideration should be made for dogs in remote forestry worksites, working dogs or any dog in remote wilderness areas due to their direct and often prolonged exposure to the elements without immediate veterinary help.
Every attempt should be made to minimize a dog’s risk of heat stroke during extreme heat events through:
adequate shade and protection
ventilation
free access to water
limiting exercise is imperative during the hottest hours of the day
Hyperthermia is an elevation in body temperature above the normal range.
Heat stress is a worsening condition that can progress to a more severe heat-related illness: heat stroke.
Heat stroke occurs when a dog can no longer maintain a normal body temperature due to the inability to effectively dissipate heat. This can be life-threatening as it affects nearly all bodily systems, internal organs and brain function. A dog suffering from heat stroke should be seen by a veterinarian for treatment and monitoring as many consequences of heat stroke do not appear until several days after the initial incident. The most common incidence of heat stroke occurs after a dog has been confined in a hot vehicle unattended.
Brachycephalic/flat-faced/shortened-muzzle dogs such as pugs and bulldogs are unable to pant as effectively and are therefore more susceptible to overheating. Overweight, elderly, immunosuppressed dogs and puppies are also at an increased risk of overheating in extreme temperatures.
THERMOREGULATION IN DOGS
Dogs do not maintain body temperature - or thermoregulate - the same way humans do. The primary method to cool down is evaporative cooling of the tongue through panting. A dog’s tongue increases in surface area and its respiration rate increases, which causes heat to dissipate from the body. Additionally, dogs release heat through sweat glands in their paws and ears. It is a common misconception that long-haired/double-coated dogs should have their coats shaved in hot weather. The coat, however, is an effective heat-regulating mechanism that can be interrupted if shaved. Additionally, a healthy coat is an efficient thermoregulator. Maintaining a balanced diet, frequent brushing and bathing, and supplements such as Omega fatty acids will not only improve the health of the coat but also its ability to dissipate heat as needed.
Temperatures <20 degrees celsius: significantly less risk and occurrence of heat stress.
Temperatures 20-32 degrees celsius:: dogs are at risk of heat stress/heat stroke if exercised too rigorously, especially large breeds, obese dogs, brachycephalic/flat-faced breeds and puppies.
Temperatures >32 degrees celsius: Dangerous for all, regardless of age, size, breed or health status. All exercise should be avoided and precautions should be taken to minimize risk.
HEALTH EFFECTS OF HEAT STROKE
● Organ failure, including liver and kidney damage
● Bleeding disorders
● Brain damage - in some severe cases, may be permanent
● Stomach and intestinal ulceration
● Heart and lung failure
● Death
RECOGNIZING + PREVENTING HEAT STROKE
Limit exercise during extreme heat. If possible, keep your dog in a cool, well-ventilated area with ample shade and water during the hottest hours of the day. Temperatures are coldest at dawn or dusk.
Ensure you have adequate water for yourself and your dog if working away from a reliable water source.
Expect you will need a minimum of 4L of water for a dog on a hot day.
Do not leave dogs unattended in vehicles for any amount of time on warm days. There is no set temperature at which it is safe for a dog to be unsupervised while in a vehicle. The behaviour of the dog also plays a role in heat stress if they are active or anxious when left alone.
Add water to food, or offer wet food slurries to encourage fluid uptake.
Avoid prolonged exposure to direct sunlight or intense heat.
Offer frozen treats, such as frozen broth popsicles.
Familiarize yourself with your dog’s normal vital sign ranges to evaluate how well your dog’s physical system is functioning. If an emergency arises, it is important to know how significantly different the vitals are.
Temperature (normal range: 37.8-38.9 celsius) Body temperature is taken rectally. A rectal thermometer is an important item in any dog-specific first aid kit.
Heart rate/Pulse (normal range for large dogs: 100-160 BPM, medium: 80-120 BPM, small: 90-140 BPM) A dog’s heartbeat is easiest felt on the left side of the chest. Record the number of beats felt in 15 seconds and multiply by 4 for a total beats per minute (BPM).
Respiration (normal range: 15-30/min) - visualize the rate, depth, sound, and ease of Breathing
Mucous Membranes (pink and moist) - some dogs have black pigmented mucous membranes in their mouth/gums, in this case, assess the colour and hydration of the tongue
SIGNS ASSOCIATED WITH HYPERTHERMIA & HEAT STROKE
 | Skin tenting test: can be done by grabbing the fur on the scruff of a dog's neck and pulling up and away from the body. Adequately hydrated: the skin's natural elasticity will pull the skin back to the body. Dehydrated: the skin and fur stay "tented" for >2 seconds. |
 | Capillary refill time (CRT): Lift the dog's lips to see the gums above the upper teeth. Press down on the gums to blanche (decrease blood supply) the skin. Release pressure. Adequate CRT: The colouration returns in under 2 seconds. Compromised CRT: The colouration takes >2 seconds to return. A prolonged CRT occurs if the body's blood flow is compromised. This can occur if a dog is in or going into shock. |
RESPONDING TO AN ANIMAL IN HEAT-RELATED DISTRESS
Remember to take appropriate safety precautions when approaching a dog in distress. Even your own dog may become aggressive out of fear. If possible, seek additional help.
Remove the dog from the heat and out of direct sunlight.
Do not directly apply ice. This constricts blood flow which will inhibit cooling.
Provide external cooling with tepid-cool water by soaking towels placed on the head, neck, abdomen, armpit and groin. Frequently remove the towel, wring it out and then soak again in cool water and repeat.
If running water is available, pour water or use a hose to run water over the dog’s body. *Do not submerge in cold water. Cooling too rapidly can send a dog into shock*
Fan vigorously to promote evaporation (electric fans or using a makeshift fan i.e., cardboard).
Offer water to drink, if they are unable to drink - wet their lips, gums or tongue. Do not try to force water intake if the dog is non-compliant or unconscious.
Douse gauze pads with isopropyl alcohol and apply to paw pads to speed up evaporation.
Contact an emergency veterinarian. It is imperative to know your nearest emergency veterinary clinic while in the bush, as many rural communities or cities do not have 24-hour care.
OTHER SAFETY REMINDERS TO CONSIDER
Hot asphalt can cause significant skin destruction in under 60 seconds. Avoid walking on hot asphalt during the hottest hours of the day. Burnt, blistered pads can take a long time to heal and are often very painful for dogs.
Dog food, especially raw food, spoils much easier in hot temperatures. Ensure food bags are sealed in cool temperatures while avoiding direct heat.
Consider the subsequent risks of extreme heat weather events, such as catastrophic forest fires. It is always advised to have an emergency plan and emergency preparedness kit ready to go in the event of sudden evacuations or displacement.
2 weeks' worth of food and clean drinking water (4 litres of water/day)
First aid kit, medications
Carriers, leashes, collars, harnesses, muzzles
Identification, including a record of microchip/tattoo/license numbers
Waste supplies (poop bags)
Bedding, towels, blankets and toys
Contact information for the nearest veterinarian and nearest 24hr emergency veterinary clinic
*Use of this information does not replace veterinary care. It is meant as a guide only, to provide relevant information to better inform dog owners to make the safest and most appropriate decisions when preventing heat stroke, or responding to an urgent situation involving an overheating dog. In any suspected heat stroke incident, it is advised to immediately transport the animal to emergency veterinary care.
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