Heatstroke causes a severe rise in your pet's body temperature and occurs due to elevated temperatures in the environment or from performance of strenuous activity. Unfortunately the summer time allows for a combination of the two and an increase in the cases of heatstroke. It can happen as quickly as 30 minutes and is worse in places with increases in humidity, especially if there is no access to shade or breaks to rest and cool down.

Dogs cool off mostly by panting as air contacts the mucous membranes of the upper airways and allow evaporative cooling to occur. With high humidity, the evaporative cooling mechanism is not as effective. Short nosed breeds such as Bull Dogs that suffer from brachiocephalic syndrome (partially opened nares or long soft palates among other things) or dogs suffering from other upper airway problems (such as collapsing tracheas or laryngeal paralysis) are at greater risk for developing heat stroke as their main cooling mechanism is not in top shape.

Signs of heat stroke can include excessive panting, collapse, seizures, excessive salivation, vomiting, and diarrhea and occur after exercising on a hot day or being left in a car even if the windows are cracked.  Permanent and life-threatening damage to organs such as the kidneys, liver, intestines and brain can occur if not treated immediately.

If you suspect your pet is suffering from heat stroke move them into a shaded area, wet them down with COOL water and call your veterinarian immediately to let them know you are on your way. Using COLD water will only make things worse as the outer blood vessels which are helping to cool your pet down will close off. Fans or air conditioning will also help with cooling.

Your veterinarian may need to obtain baseline blood work to evaluate for organ damage, place an IV catheter and administer fluids and other medications as well as hospitalize and monitor your pet. OVERCOOLING can be more harmful than helpful and this is why it is recommended to start the cooling process and go to your veterinarian immediately for careful monitoring and adjustment to treatments as necessary.  Studies reveal that pets that present to their veterinarian soon after are more likely to survive than animals seen later. Pets that survive the first 24-48 hours of hospitalization generally do well.

I have seen cases of heatstroke in dogs left in a car WITH THE WINDOWS OPEN for only a couple of minutes, dogs going about their usual outside play on a hotter than normal day and dogs taken on long runs and hikes.

Be safe this summer and remember that if you are enjoying a nice day out with your pets to allow rest breaks, access to shaded areas, plenty of water and know when to stop! If you have any concerns at all see your veterinarian, it's always better (and cheaper) to be on the safe side!

Dr. Julio Lopez practices at the world renowned California Animal Hospital Veterinary Specialty Group in West Los Angeles. He is a graduate of the College of Veterinary Medicine at Cornell University.  You can find more expert veterinary advice from Dr. Lopez on his blog, ExpertVet, and follow him on Twitter at @expertvet.