We’ve all be told of the dangers of leaving your dog in an enclosed space such as a hot car. But what about day to day activities outside- how do you know how much is enough? And what is heat stroke?
Dogs are especially prone to hyperthermia (an abnormally high body temperature) because they do not sweat and are therefore unable to dissipate heat like humans. In extreme cases, the temperature rises to dangerous levels and results in multi-system organ failure (meaning all of the vital organs begin to shut down).
Many Things Can Cause Heat Stroke
Environmental heat isn’t the only thing that can cause heat stroke. Other causes of the illness include: Seizures, anesthetic complications, hormonal diseases (hyperthyroidism), poisoning via slug and snail bait and other exposures. This article however will focus on environmental exposures. Usually heat stroke occurs in the setting of both increased exogenous heat and decreased ability to dissipate heat.
Most Common Exposures
Despite raised awareness, dogs being left in enclosed unventilated areas still account for a large percentage of heat related illnesses. This includes dogs left in unventilated cars, cages, and small rooms. Areas that reflect heat (such as asphalt only areas) and places without shade (ie: the beach) can become dangerous places if the proper precautions aren’t taken.
Recognizing The Signs
Signs and symptoms of both fever and non-fever hyperthermias include:
- Excessive panting
- Increased temperature (>103F)
- Decreased urine output
- Ptyalism (Excessive drooling)
- Reddened gums
- Tachycardia (Rapid heart rate)
- Tachypnea (Rapid breathing)
- Altered Mental Status
- Ataxia (Poor coordination, impaired gait)
- Muscle tremors
As heat stroke sets in, organ systems begin to fail. And yes, it’s as scary as it sounds.
In the initial stages, the blood vessels dilate. Cardiac output (the amount of blood being pumped out by the heart), initially increases. This is the body’s initial attempt at compensation. As the illness progresses, blood begins to pool in the body and the total amount of circulating blood decreases. With this, the body’s protective mechanisms that normally maintain temperature continue to fail, and heat stroke ensues.
First, thermal injury causes damage to blood vessels. Normal clotting function is impaired and dogs may develop Disseminated Intravascular Coagulation– a fancy way of describing abnormal platelet function, resulting in life threatening clotting and bleeding.
The kidneys sustain injury from dehydration, DIC, and later due to having to excrete the byproduct of muscle breakdown.
The liver sustains direct thermal injury which results in widspread cell death. True failure (in both dogs and humans) will result in buildup of toxins normally cleared by the liver, decreased production of clotting factors normally produced by the liver, and inability to regulate blood glucose levels.
First, mental status changes may be mild and caused by dehydration. These may get progressively worse if the dog’s blood pressure drops to a dangerously low level. In humans, the definition of heat stroke is “hyperthermia with the presence of neurologic dysfunction.” Dogs however may have heatstroke and be seemingly neurologically “normal.” Their brains seem to be more resistant to injury induced by heat, and they may not develop neurologic symptoms until later in the illness. Thus, just because your dog’s behavior is “normal” does not mean that he/she does not have heat stroke.
If this was more information than you bargained for, please take away this:
-heatstroke is a life threatening illness
-it may affect all of the major organ systems
-dogs manifest heat stroke differently than humans do
-mental status changes is heat stroke may present later in dogs than in humans- just because your dog is behaving normally now, doesn’t mean that he does not have heat stroke
If you want more details, here is an excellent journal article on Canine Heat Stroke.
If You Think Your Dog May Have Heat Related Illness
-Get him out of the sun into a cool environment
-Do your best to get him to lay down, calm him. If there is a pool near by for him to cool off in, encourage this
-If he is able to drink, encourage him to do so. Do not “force feed” him water. It may go in his lungs and cause him to aspirate
-Take his temperature. If >103 (What is considered to be the danger zone), call your veterinarian for advice immediately.
The best thing you can to to protect your dog is learn the key methods of prevention, and recognize the early signs of heat exhaustion!
- Keep your dog inside on very hot days. If he wants to be outside, always make sure he has adequate access to shade. If you are at a place without shade (the beach for example), put up a tent or umbrella for him to take cover under.
- Allow unrestricted access to water
- Restrict exercise. YOU can sweat to dissipate heat. He can’t!
- Set up a pool for him outside to cool down in periodically- he’ll love you for it!
- Never leave your dog in a parked car when it is hot out. Even in the “shade”. You wouldn’t believe how hot your car will heat up.
- Don’t muzzle your dog. Panting helps regulate body temperature, and muzzling interferes with this.
- Use extra caution if your dog is at the extreme of age- very young, or senior. These are dogs are at the highest risk.
- Remember that dogs who have had heat related illness in the past are at higher risk for developing it again on even less hot/humid days.
- Brachycephalic (flat-faced) dogs ie: bulldogs are at very high risk. Heavy exertion and extremes of temperature is especially dangerous in these dogs. (Remember, they tend not to be very adept swimmers either, so shallow water and supervision is key!)