Heat Stroke: Keep Your Dog Safe in Hot Weather

Laurie Anne Walden, DVM

Summer is rapidly approaching, and it’s already hot outside. Even when the weather is moderately warm, the temperature inside a parked car can rise dangerously high. Heat and humidity put dogs at risk of heat stroke, which can be fatal.
 
Dogs rely mostly on panting to cool themselves (they sweat only a little from their paw pads). But panting isn’t always enough to keep a dog’s body temperature in the normal range, from about 100°F to 103°F. As the body temperature rises above normal, dogs can develop heat exhaustion. Heat stroke (in dogs) is defined as a body temperature over 105.8°F along with central nervous system dysfunction.
 
Heat stroke is a serious medical emergency and has a reported death rate of about 50% in dogs. It damages the brain, kidneys, heart, intestines, and other internal organs, and it causes blood clotting disorders.
 
Causes of heat stroke
Heat stroke is caused either by exposure to heat and humidity or by strenuous physical exertion. These are situations that commonly lead to heat stroke in dogs:

• Leaving a dog in a parked car (cracking the windows open doesn’t help)
• Running, hiking, rollerblading, or even taking long walks with a dog in hot, humid weather
• Leaving a dog outdoors in the heat without enough water and shade

 
Justine Lee, DVM, DACVECC, an emergency veterinary medicine specialist, recommends not exercising with your dog if the temperature (in Fahrenheit) plus the humidity level is over 150. So when the temperature is 80°F and the humidity level is 80%, it’s too hot to take your dog on a run (80 + 80 = 160).
 
Dogs at risk
Although any dog can develop heat stroke, the risk is higher in dogs with these conditions:

• Obesity
• Brachycephalic head shape: flat-faced dogs like pugs, French and English bulldogs, and Boston terriers
  
• Heart disease
• Lung or airway (especially larynx) disorders
  
• Nervous system disease

 
Signs of heat stress
Dogs start showing signs of heat exhaustion before they develop full-blown heat stroke. Watch for the warning signs, which become more severe as heat stroke sets in:

• Excessive panting
• Fatigue
• Fast heart rate
• Dry/sticky gums
• Dark red or purple gums or tongue
• Stumbling or seeming dizzy
• Vomiting
• Difficulty breathing
• Seizures
• Collapse
• Dark or red urine
• Black diarrhea

 
If you see signs of heat exhaustion in your dog, carry him to a cooler place immediately; at least get him into the shade. Wet him down with cool water (ice is not necessary) and give him water if he’s able to drink on his own. Take him to a veterinary clinic right away if he has any of the more severe signs or if you’re not sure whether he’s OK after a few minutes. It’s much better to take in a dog who turns out to be fine than to delay treatment for a dog who has heat stroke.
 
Preventing heat stroke

• Never leave a pet in a parked car.
• In summertime, exercise with your dog in the early morning or the evening.
• Carry water for your dog to drink when you’re exercising together.
• Provide shade and water for outdoor dogs (an enclosed doghouse is too hot).
• Keep your dog at an ideal weight.
• Do not leave a brachycephalic dog outdoors in hot weather.
• Keep an eye on working/hunting dogs and give them water and shade breaks. They tend to focus on their tasks and don’t know when to stop.
• Plan ahead for power outages and air conditioner malfunctions.

 
Sources

• Bruchim Y, Klement E, Saragusty J, Finkeilstein E, Kaas P, Aroch I. Heat stroke in dogs: a retrospective study of 54 cases (1999-2004) and analysis of risk factors for death. J Vet Intern Med. 2006:20(1):38-46.
  
• Lee JA. Keep your dog cool this summer: heat stroke, part I. Pet Health Network website. http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/keep-your-dog-cool-summer-heat-stroke-part-i. Accessed June 6, 2018.
  
• Lee JA. Keep your dog cool this summer: heat stroke, part II. Pet Health Network website. http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/keep-your-dog-cool-summer-heat-stroke-part-ii. Accessed June 6, 2018.
  
• Marshall M. Heat stroke: diagnosis and treatment. DVM360 website. http://veterinarynews.dvm360.com/heat-stroke-diagnosis-and-treatment. Published August 1, 2008. Accessed June 6, 2018.
  
• McLaren C, Null J, Quinn J. Heat stress from enclosed vehicles: moderate ambient temperatures cause significant temperature rise in enclosed vehicles. Pediatrics. 2005;116(1):e109-112.
  

 
Photo by Kasia Koziatek

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