None of my dogs have ever done terribly well in summer. Freddie and Yogi would out and out refuse to go for walks. They'd get to the bottom of the driveway and sit. Nothing no how was going to make them go any further. Once you turned around and started back towards the house, they got up and followed very obediently.
If you do walk your dog in summer, after dark or early, early morning are the best times.
These two are a bit different. Baxter won't go out in direct sun at all. We call him the vampire dog. He'll burn up if the sun hits him.
He will also fight you about going outside if he feels it's warm out there when you open the door. He doesn't like getting wet, so a pool isn't going to do anything for him. We keep him well brushed in summer and he drinks a lot of water out there in summer as well. His best times to get outside are very early morning, I mean like before 6am and after dark when it's cooler although I do make him go out midday to relieve himself whether he wants to go out or not.
Bentley on the other hand hops into the pond when he's hot. We tried a kiddy pool for him when he was little, but he prefers the pond. He doesn't know when to quit in the heat and we have to watch him because I can see him getting heat stroke if he's not watched.
Smaller meals in summer are important too, as they don't get the same exercise in most cases. If you have a sunny yard, make sure there is shade for them if you're going to keep them outside with you for any length of time as well.
clm