Heat-Related Illness in Dogs

We are currently in a heat wave. It has been intense, although I know that it pales in comparison to heat waves in other regions of the world. Sharing my space with both dogs and cats, I have been very careful to keep them healthy in this weather. Lots of available water, frozen treats, no walks above recommended temperatures, no leaving them in cars, etc. I’m fortunate in that I have a fair amount of dog training skills as I volunteer as a puppy raiser with a service dog training organization and I like getting creative (the puppy Olympics are coming in my house). But I worry when I see people out walking their dogs at unsafe temperatures and I worry about the people who keep their dogs at home but don’t do anything to stimulate them in that space. A bored dog can be a frustrating dog.

The thing is that extreme heat events are expected to increase in both frequency and severity due to climate change. Human deaths due to heat-related illness are expected to triple by 2050 in England (House of Commons Environmental Audit Committee cited by Hall, Carter, and O’Neill, 2020). But, there are very few studies on animals. Hall, Carter, and O’Neill (2020a) looked at the risk factors for heat-related illness in dogs. They found that increased body weight (relative to breed), brachycephaly (think of dogs with squished or flatter faces), and age all increased risks. This means that managing obesity in dogs will become even more important (a problem if those dogs are getting less exercise because they can’t get outside because of the heat). It also means that some breeds, like bulldogs, will be at greater risk than others.

In another study about dogs, Hall, Carter, and O’Neill (2020b) found that while we often hear about the harms of leaving dogs in cars as the cause of heat-related illness and death, they only accounted for 5.2% of illnesses in dogs in the UK. By far, exertional heat-related illness was the most common trigger at 74.2% of cases. The same risk factors apply for this group as well, and the odds of death are the same for both exertional related and being left in a car. This is so important because, as I’ve been seeing, many people are still taking their dogs out during heat waves and letting them run in dog parks, playing fetch, and other types of exertion. Even in my house, given that I am without air conditioning, I’m aware of keeping the training sessions short, especially if I’m having them do high-energy activities.

What do the animals know? Palestrini and colleagues (2022) surveyed dog and cat owners in Italy regarding how their animals’ behaviour changed during intense weather events. The good news is that the animals themselves show some signs of adaptation with sleeping more during hot weather. Also good news is that weather events didn’t impact aggressive or house soiling behaviours. The authors point out that there needs to be societal changes and owner education to support pet health in the face of climate change.

I hope to see more research on this and more subsequent guidance. I think the finding that the great majority of cases of heat-related illness in dogs were related to exertion is something that needs to be promoted more. As the authors said, there needs to be greater education that dogs don’t just die in hot cars.

In the meantime, the guidelines that I use are:

• if the pavement is too hot for the back of my hand, it is too hot for their paws
• keep lots of water available
• use frozen treats
• offer cool places for them to rest
• brain games are important and can help stimulate your dog without requiring lots of physical exertion
• adjust feeding based on activity level
• early morning and late evening are your friends but check the temperature because it doesn’t always drop low enough
• don’t rely on a fan (they don’t help dogs as much because they mostly sweat through their feet)
• use cooling mats, vets, etc or give your animal a chance to cool off in a pool or with a hose (but watch for spots that don’t dry to prevent skin irritation and ear infections)
• keep your animal a healthy weight

And watch for signs of heatstroke, including, heavy panting, glazed eyes, rapid heartbeat, difficulty breathing, excessive thirst, lethargy, lack of coordination, vomiting, profuse salivation, fever, dizziness, tongue colour change (gets darker), seizure, and unconsciousness.