Heatstroke in dogs

We are all looking forward to Summer so we can enjoy the outdoors again with family, friends and our dogs.

Last summer the average day temperature in the Waikato (from Dec 2021- Feb 2022) was 23-25 C, but it appears that the weather patterns are changing. Europe had massive heatwaves in the last months, with temperatures in the high 30ies and even lower 40ies, and heatstroke (in people and pets) has been of great concern. Heatstroke can occur when the outside temperature rises with no way of cooling down.

 In NZ we mostly see heatstroke in dogs that have been left in locked cars while the owner quickly has gone to the shop to get ‘just a few things’.

Car heat to outside temp over time ratio

It is quite sobering to see how quickly the temperature rises inside a locked car over a short amount of time.  If it is 23.9C outside, and your shopping took a bit longer because of waiting at the checkout or unexpectedly catching up with someone, you’ll find the temperature in your car after 30 minutes is now almost 43C.  If we hit warmer weather and it is 30C outside, the car would be over 48C in that same amount of time.

Dogs can also get heatstroke from strenuous exercise or activity (hiking, hunting, jogging), or as a result of seizures (toxins, epilepsy). Dogs are even more at risk of overheating if they have a short nose (pugs, English Bulldog), are overweight, have a thick coat, are very young or old, or have breathing conditions.

What does a dog with heatstroke look like?

Dogs may initially appear stressed and they may be unsteady on their feet. They will be panting and or drooling. The gums may be bluish or very red, some may get bloody diarrhoea or vomit. This may be followed by lethargy and collapse, progressing into seizures, coma and ultimately death. Body temperatures over 42.5C are usually fatal.

How to help my overheated dog?

If your dog appears to be severely overheated, you can start cooling your dog down on the way to a vet clinic. Pour cool or lukewarm water over the groin, neck and armpits. Don’t use cold water or iced water as this will constrict blood vessels and will delay the cooling process. Offer cool drinking water and use car vents or fans to blow air on the dog.  

How to minimize the chance of heatstroke?

Do not take your dog if he/she is going to be left alone in the car with locked windows. You can keep your car cooler by parking your car in the shade, using reflective sun shades in your windscreens, keep windows and or sunroof partly open to get air circulating and install a solar-powered window fan to draw outside air into the car.  

  • Walk dogs early in the morning or later in the evening, which will also prevent burned footpads, and avoid strenuous exercise.
  • Groom hairy dogs to remove excess fur.
  • Carry cold water and a collapsible bowl on walks.
  • Use cooling mats in baskets and cooling vests on walks.
  • Make frozen treats.
  • Get a cheap play pool - Other pets will also appreciate having cool areas to hang out when the temperature rises.

Dr Asse Bosch BVSc BSc



Franklin Vets

Franklin Vets - excellence in veterinary care for dairy, farming, lifestyle, equine and household pets. BESTPRACTICE ACCREDITED NZ.