Running during the dog days with your dog can be done if you apply a smidge of common sense and understand two things.
First, you are biologically engineered to be an efficient running machine in heat. Your a pro at sweating, you provide a small profile to the sun and you're not covered in fur.
Second, none of these apply to your pooch. Given an option, dogs will elect to siesta during the worst of the heat and, if they do venture into the heat, don't have the same mechanisms to reduce their heat load that you do.
For starters, your dog does not sweat. Most animals don't. They eliminate heat by panting which is why even a fit dog will huff and puff in the backyard following you as you garden. Short-nosed breeds (think pug or bulldog) have a harder time reducing heat.
Dogs (and most animals) also present a very large portion of their body to the sun. This leads to a bigger surface to absorb heat - especially in direct sun. The darker the fur, the more heat they'll pick up.
Speaking of fun, did you consider throwing on that heavy jacket before a run in a triple digit heat wave? Didn't think so (unless you're training for Badwater)! Your dog has no choice...
So, here's a few tips for you and your dog.
1. Run during the early morning and late evening hours. It's cooler and the sun is far less direct which will make both of you more comfortable.
2. Plan on slowing down. The faster you try to run, the more heat you generate and the harder it is to bleed it off. That doesn't just apply to the dog - you're body is sending a lot of extra blood to the skin to try to cool it. Give your body - and your dog - a fighting chance. Walking breaks are fine for both of you.
3. Take lots of water for both of you. Put ice in it before you leave.
4. Run in shade whenever possible. This is a great time to get off of the hot pavement and get onto trails.
5. Remember that the dog doesn't have fancy training shoes - hot pavement can literally burn their paws.
6. Keep it short - longer runs increase the risk to your dog as the heat builds up.
7. Going near some clean water like a lake or a river? Think about letting them splash around. Splash with them - it was fun when you were three and it's still fun now.
Enjoy the summer, you and your dog - just be safe.
Run gently, friends.