Heat Stroke and Dehydration in Dogs

Heat stroke is an emergency and requires immediate treatment. Because dogs do not sweat (except to a minor degree through their foot pads), they do not tolerate high environmental temperatures as well as humans do. Dogs depend upon panting to exchange warm air for cool air. But when air temperature is close to body temperature, cooling by panting is not an efficient process.

  • Common situations that can set the stage for heat stroke in dogs include:
  • Being left in a car in hot weather
  • Exercising strenuously in hot, humid weather
  • Being a brachycephalic breed, especially a Bulldog, Pug, or Pekingese
  • Suffering from a heart or lung disease that interferes with efficient breathing
  • Being muzzled while put under a hair dryer
  • Suffering from a high fever or seizures
  • Being confined on concrete or asphalt surfaces
  • Being confined without shade and fresh water in hot weather
  • Having a history of heat stroke

Heat stroke begins with heavy panting and difficulty breathing. The tongue and mucous membranes appear bright red. The saliva is thick and tenacious, and the dog often vomits. The rectal temperature rises to 104° to 110°F (40° to 43.3°C). The dog becomes progressively unsteady and passes bloody diarrhea. As shocksets in, the lips and mucous membranes turn gray. Collapse, seizures, coma, and death rapidly ensue.

Treatment: Emergency measures to cool the dog must begin at once. Move the dog out of the source of heat, preferably into an air-conditioned building. Take his rectal temperature every 10 minutes. Mild cases may be resolved by moving the dog into a cool environment.

If the rectal temperature is above 104°F, begin rapid cooling by spraying the dog with a garden hose or immersing him in a tub of cool water (not ice water) for up to two minutes. Alternatively, place the wet dog in front of an electric fan. Cool packs applied to the groin area may be helpful, as well as wiping his paws off with cool water. Monitor his rectal temperature and continue the cooling process until the rectal temperature falls below 103°F (39°C). At this point, stop the cooling process and dry the dog. Further cooling may induce hypothermia and shock.

Following an episode of heat stroke, take your dog to a veterinarian as soon as possible. Heat stroke can be associated with laryngeal edema. This seriously worsens the breathing problem and may require an emergency tracheostomy. An injection of cortisone before the onset of respiratory distress may prevent this problem.

Other consequences of hyperthermia include kidney failure, spontaneous bleeding, irregular heartbeat, and seizures. These complications can occur hours or days later.

Dehydration

Dehydration occurs when a dog loses body fluids faster than he can replace them. Dehydration usually involves the loss of both water and electrolytes. In dogs, the most common causes of dehydration are severe vomiting and diarrhea. Dehydration can also be caused by inadequate fluid intake, often associated with fever and severe illness. A rapid loss of fluids also occurs with heat stroke.

A prominent sign of dehydration is loss of skin elasticity. When the skin along the back is pulled up, it should spring back into place. In a dehydrated animal, the skin stays up in a ridge.

Another sign of dehydration is dryness of the mouth. The gums, which should be wet and glistening, become dry and tacky. The saliva is thick and tenacious. In an advanced case, the eyes are sunken and the dog exhibits signs of shock, including collapse.

Treatment: A dog who is visibly dehydrated should receive immediate veterinary attention, including intravenous fluids, to replace fluids and prevent further loss.

For mild dehydration, if the dog is not vomiting you can give him an electrolyte solution by bottle or syringe into the cheek pouch. Balanced electrolyte solutions for treating dehydration in children, such as Ringer's lactate with 5 percent dextrose in water or Pedialyte solution, are available at drugstores and are also suitable for dogs. Gatorade is another short-term substitute to help replace fluids. Administer the solution at a rate of 2 to 4 ml per pound (1 to 2 ml per kilo) of body weight per hour, depending on the severity of the dehydration (or as directed by your veterinarian).

This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.