Okay it's beautiful Summer...long hot days, barbeques.......
Number one: Heat exhaustion. Yes dogs do get it. Hate to be a nag or boring for all you who know this by heart, but new dog-owners may not realize that dogs can get heat exhaustion and heat-stroke quite easily. So NEVER ever leave a dog, for any amount of time, in a car. Even with the windows open a little Even if there is water available. Those won't help when the temperature gets as hot as an oven inside. Dogs die and quite quickly in parked cars. Parking in the shade of a tree....think about it. How long are you going to be? If 5 minutes or so, fine. If longer -forget it. What is now shade may be full sun in half an hour when the sun has moved!
Leave your dog at home. Even if it's bored it will be safe.
Barbeques: Do not go well with dogs. Guests often slip treats to begging canines! Do you really want your dog getting a bout of pancreatitis because it ate too much buttered corn? Or just getting too much human food which is laden with salt and fat?
River water: Beware! My dog had a terrible bout of diarrhea a couple of weeks ago because she gulped river water downstream of farmland. She was lucky. She's ok now. River water can contain very nasty parasites and infections. Yet it might look quite clean. And be very tempting for a dog to swim in and drink. I guess that all depends where you live, and what the river is like.
Exercise: Some dogs have no sense. They are happy to race about full-pelt even when it is 100 degrees!! Don't let them. In heatwave weather dawn and dusk are the best times for running. Rest of the time....boring I'm afraid!
In extremely hot weather it can be a good plan to take a small backpack on dog walks, containing a large-ish plastic bottle of tap water, and a little drinking dish. I use a plastic drip tray because it's light to carry (wouldn't it be good if dogs appreciated you carrying all their equipment for them?!) If I see my dog is getting a little overheated I give her a drink, and put some water on her fur. Don't throw the water on all at once. That can come as a bit of a shock. Put it on gradually till the dog's fur is nice and wet. This will catch any breeze and help cool dog down.
Okay that's my little lecture over, so I'll shut up now :-) Happy hot-dog days!