Houston has an average of 99 days per year above 90 degrees Fahrenheit. The heat and humidity levels we see here are very similar to those seen in tropical climates. Air-conditioning is a way of life for most of us much of the year. It is actually vital for the survival of the people and pets of Houston.

Heatstroke in pets is a rapidly progressive life-threatening emergency. It is a state of extreme hyperthermia (106-109 degrees F), resulting in thermal injury to the body’s tissues. Although uncommon in cats, it occurs frequently in dogs. This is especially true for dogs who are overweight, have upper airway obstruction (i.e. brachycephalic breeds, laryngeal paralysis), or those that are exercised in hot, humid weather. Heatstroke can also occur in pets deprived of water or shade outdoors, confined in areas without proper ventilation, and during the blowdrying process after a bath.

With an outside temperature of 90 degrees Fahrenheit, the inside of a car becomes 109 degrees within 10 minutes, and after 20 minutes, the internal temperature rises to 119 degrees. 30 minutes brings us to 124 degrees, and after 60 minutes, the inside of your car reaches 133 degrees.

Tissue damage occurs when core body temperatures are above 107 degrees F for a significant amount of time. Body temperatures above 110 degrees can result in death within minutes. Kidney failure, bloody diarrhea/vomiting, systemic inflammation, sepsis, brain swelling, low blood sugar, seizures, blood clots, bleeding disorders, and liver and heart necrosis can occur with heatstroke.

The overall mortality rate of heatstroke in pets is 50%. Some animals that do survive end up with permanent neurological problems. Breeds predisposed to heat stress include: Anatolian Shepherds, Brachycephalic breeds (short-nosed), Bulldogs, Saint Bernards, and Weimaraners. Older dogs are more susceptible than younger dogs.

If an emergency facility is more than a few minutes away, it is advised that owners start cooling efforts in the event of a heatstroke. This would include immersing the pet in cool water using either a tub or spraying with a garden hose. DO NOT USE ICE WATER – this can cool the pet too quickly and cause further complications. A fan can be used to increase cooling after wetting. Rapid cooling should cease when the body temperature reaches 103 degrees. Have cool water available, but do not force water into your pet’s mouth. Transport your pet to the nearest emergency facility as soon as possible.

A majority of heatstroke patients end up in ICU on IV fluids. Some require oxygen, blood plasma transfusions, or treatment for brain swelling, kidney and or liver failure, gastrointestinal damage, and other conditions that occur as a result of thermal injury.

Preventative measures that can be taken to reduce the incidence of heatstroke include:

  1. Do not cage animals outdoors without adequate shade or water
  2. Keep pets indoors at very high temperatures
  3. Do not leave pets in closed compartments (including cars) exposed to the oven effect of the sun. HEATSTROKE CAN OCCUR IN PETS LEFT IN CARS ON RELATIVELY COOL DAYS (70 degrees Fahrenheit)
  4. Take special precautions with old, overweight, ill or immobile pets.

Please keep this information in mind as summer in Houston approaches. Remember that heatstroke can occur even on milder days, and on hot, humid days, it can result in death within minutes. If your pet is experiencing heat stress, transport him/her to a veterinary emergency clinic immediately. If the trip will take longer than a few minutes, consider cool water therapy and a fan prior to transport. Draping your pet with a cool water-soaked towel in an air-conditioned car on the way to the clinic may help prevent further thermal injury.