A college-age boy is home for April break and takes the family’s 5-year-old black Lab “Gus” on a three mile jog. Gus faithfully completes the distance, despite not stopping and not being offered water. Home that evening, Gus becomes weak and has trouble rising. The family brings Gus to the emergency veterinary service, at which time he is recumbent and poorly responsive with a mild increase in body temperature.
By Jennifer Roberts
Heat stroke develops when the body’s temperature rises more quickly that the body can cool itself. It can occur during exercise or when an animal is confined without adequate shade and water. Elevated body temperatures can result in shock and organ damage, including kidney failure and seizures due to injury of the tissues.
Heat stroke is a life-threatening condition that requires emergency intervention. Surprisingly, it occurs more commonly in springtime, when environmental temperatures are relatively mild and humidity is not a significant factor.
There are several common medical diseases as well as breed-specific conditions which place dogs at risk. The purpose of this article is provide dog owners with a basic understanding of heat related injuries and the tools for preventing heat stroke.
A variety of factors can put both people and pets at a greater risk for heat stroke. examples of physical limitations include being overweight, in poor physical health and old age. Dogs with dark coats absorb heat, while thick coats limit a dog’s ability to cool.
Other less obvious physical factors include breeds such as Bulldogs, Boxers, Pugs and Boston Terriers whose short snouts and small nostrils dramatically limit their ability to cool. Pets with a history of heart disease, thyroid disease and upper airway diseases (laryngeal paralysis, collapsing trachea) also have a reduced capacity to cool efficiently.
Situations that can lead to heat stroke in pets include confinement without adequate shade, a lack of ventilation and lack of water. Animals should never be left alone in vehicles in warm weather, even if the windows are left open. Dogs in open truck beds may be at risk for heat stroke as well, because in addition to a lack of shade, dark bed-liners and metal bottoms absorb the sun’s heat from which pets can not escape.
Besides avoiding unsafe situations that put a dog at risk for heat stroke, there are a number of things you can do to reduce a dog’s risk for developing heat stroke. Gradually acclimate your dog to physical activity in warmer temperatures. Plan your pet’s exercise routine according to the weather report and avoid activity at the warmest times of the day. Restrict activity in the aforementioned breeds or with pets with predisposing medical conditions in warmer months.
Pets often dig holes in an effort to lie in the cool dirt, but when temperatures rise above 89F (31C), evaporation becomes the most important method of cooling. Unlike horses and cows, dogs don’t sweat, but rely on panting for evaporation. Panting moves a large amount of air and salvia over the tongue’s surface, but there is a limitation to the rate of cooling achieved by panting.
The clinical signs of heat stroke vary and depend on the duration of high body temperature. The exact temperature at which heat stroke occurs in dogs is not known, but rectal temperatures as low as 105.8F (41C) have been associated with permanent brain damage. Excessive panting and restlessness should raise concern for heat stroke. Seek immediate veterinary help if you see vomiting, loose stools, collapse or seizures.
If you think your pet is experiencing heat stroke, take steps to begin rapid cooling. Seek shade for your pet. Provide drinking water if your dog isn’t vomiting. Encourage your dog to lie in a lake, stream or ocean water. If you soak your pet with a hose, make sure the water penetrates down to the skin. Cool or tepid water is ideal, because very cold water will cause constriction of the blood vessels in the skin trapping heat. Use a fan or open the car windows while driving. If accessible, apply ice packs over neck and groin regions. Do not give Aspirin, Rimadyl, or other medications because they will not change the body temperature and may further damage kidneys and gastrointestinal tract.
In conclusion, there are many factors which contribute to the development of heat stroke, making it difficult to predict which animals will be affected. The clinical signs are variable and depend on the duration of elevated body temperature. Unrecognized or untreated heat stroke may lead to permanent kidney and brain damage. Confined animals must have access to shade, fresh water and ventilation at all times. Restrict your pet’s activity to cooler times of day and even well-conditioned animals should have only brief periods of exercise on hot days. If your pet is exhibiting signs of heat injury begin active cooling and seek immediate veterinary care.
Jennifer Roberts, DVM, MS is residency trained in Veterinary Emergency and Critical Care. She is the Director of Emergency Services at the Maine Veterinary Referral Center, which provides 24 hour emergency care in Scarborough
Original article printed July 2009, Volume 4, Issue 7 of DEDN
