Don’t walk your dog on hot foot paths in the heat of the day. The best time to walk your dog during summer is first thing in the morning or late afternoon/early evening.
Fresh clean drinking water every day. I always suggest having an extra water bowl out during the warmer months so if one gets knocked over there is always a back up.
Ice blocks in the back yard make a cool treat. These can even be flavoured.
Easily overheated dogs would appreciate a doggy pool. The clam shells from Bunnings make the perfect pool (or sandpit)