Heat Stroke (Hyperthermia)

It’s mid May in Texas, so we are getting ready for the triple-digit temperatures to return.  Summer is a great time to be outside with your pet, but be careful!  As humans we know when the thermometer starts to climb that we should drink plenty of water and stay in the shade, but our dogs aren’t always that careful.

Dogs are not able to sweat the way we do to cool themselves.  Apocrine glands are located around the paw pads but do not help much with cooling (one theory is that these glands help maintain traction when dogs are running).  A dog’s primary method of thermoregulation is through panting – causing evaporative cooling using the respiratory tree.  This works fairly well most of the time, but when exercising in the heat or confined without access to water, it’s easy for dogs to get too hot and into trouble.  Certainly NO dog should ever be left in a car for any length of time in summer – those get so hot so fast a major tragedy is always a possibility.  Normal body temperature in dogs is 101F.  At a body temperature over 106F, your dog can begin to experience organ damage from heat stress.

Certain dogs are more prone to developing heat stroke.  Brachycephalic breeds such as bulldogs, pugs, shih tzus, and boston terriers have more trouble with respiratory cooling and so can be overheated more easily.  Also, overweight dogs and elderly dogs have more problems keeping cool than their younger, thinner counterparts.

Hyperthermia is a time-sensitive problem.  When overheated, the body responds with vasodilation to try to let off the excess heat.  This leads to hypotension (falling blood pressure) and results in organ damage.  This hypotension can be reversed with appropriate therapy – including IV fluid therapy, gentle cooling, and medications – but the organ damage may remain.  The organs most often affected by hypotension are the kidneys, intestinal lining, liver, and brain.  About 50% of dogs with severe hyperthermia fall into coma-like states and do not recover.  These dogs also experience liver and kidney failure and severe gastroenteritis before they die.

If your dog ever shows signs of being overheated, emergency intervention is warranted. Symptoms include excessive panting, weakness, vomiting, diarrhea, collapse, and seizures. You can take your dog’s temperature with a rectal thermometer. Seek professional assistance for any dog that has collapsed or with a temperature over 105F immediately. If the reading is between 103F and 105F and your dog is still able to walk, go indoors, offer water, and place rubbing alcohol or cool (not icy) water on the pads of the feet, flanks, and ear flaps. If your dog will get into a tub, run a cool (again, not icy) bath and let him or her stand immersed. Check a rectal temperature again after a few minutes and stop cooling therapy when the reading gets to 103F. Monitor closely for diarrhea, vomiting, and lethargy, and seek professional help if any occur within 48 hours of the overheating episode.

To avoid heat stroke, make sure you monitor your dog’s general health during outdoor excursions. Try to stick to shade and avoid direct sun as much as possible. Make sure you offer water regularly and that you prevent your dog running too far or for too long. Swimming can help keep your pet cool as well. A little prevention can save you a great deal of stress and keep summer safe for everyone in the family – furry members included!

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