Mad dogs and Englishmen …
Going out in the midday sun is a very different experience depending on the species you belong to. Humans and horses have remarkably efficient cool-down mechanisms which allow us to exercise, work and play in a wide range of temperatures without issue.
Dogs, however, are very different to us, and will certainly have a more rapid and dramatic reaction to hot and humid conditions than we do. Where you can comfortably go for a long walk at lunchtime or lie on the beach, your dog will struggle, and here’s why:
The first difference is our respective ability to sweat. Dogs do sweat, but they sweat a bit differently than humans.
Dogs have two types of sweat glands: merocrine glands, which are similar to human sweat glands, and apocrine glands. Merocrine glands are located in dogs' paw pads. Sweating through their paws helps dogs cool down. The apocrine glands, located throughout your dog's body, also make dog sweat – but this type of sweat doesn't cool your pup down. Instead, the sweat from apocrine glands contains scent pheromones that help dogs identify each other. It’s like their personal perfume.
While sweating through their paws helps your dog cool down a little, the primary way they lower their body temperature is through panting.
When a dog pants, the moisture evaporates from their tongue and cools them down. Which is why, when a dog is hot, they open the angle of their mouth wide and loll their tongue further out into the air. Watch out for this as one of the first signs of heat exhaustion.
Another way dogs are able to regulate their body temperature is vasodilation. During this process, a dog's blood vessels expand, bringing hot blood closer to the skin's surface and letting it cool down. This cooler blood then flows back to the heart, bringing the dog's overall temperature down. At the same time, they change the alignment of the hairs all over their body to release the excess heat into the air and away from their skin. We don’t have a layer of fur covering our bodies so it’s much easier for us to cool down quickly.
While all dogs are at risk for overheating if the conditions are right, some breeds are more prone to it than others. This includes dogs with thick coats or long hair, very young or very old dogs, and brachycephalic breeds – those with short noses and flat faces, such as shih tzus, pugs, boxers and bulldogs. Overweight dogs and those that suffer from medical conditions that cause difficulty breathing or heart problems are especially susceptible.
The best way to prevent your faithful friend from overheating is to stay out of the sun. Walk them early in the morning and check the ground surface temperature before you set off. Take plenty of iced water and keep to the shady trails. Pay attention to your pooch and know the early signs of heat exhaustion. Prevention is better than cure with this one, trust me.
• Lucy Richardson graduated from Edinburgh University in 2005. She started CedarTree Vets in August 2012 with her husband, Mark. They live at the practice with their two children, Ray and Stella, and their dog, two cats and two guinea pigs. Dr Lucy is also the FEI national head veterinarian for Bermuda