We ran into difficulties a couple of weeks ago with our dog in France. Thinking it was cool around 9.30 am, so 8.30 am English time, we walked along the beach to a château. The dog was in and out of the sea and walking on sand. The château was beautifully cool, limestone walls and lofty rooms, but coming out 2 hours later around 1 pm, it was really boiling. We knew we had to get back somehow, so we gave the dog water to drink from his bottle and our own water too. At least we didn't have to walk on pavements, but the silver sand was prickly and we could tell he was uncomfortable. We tried to find the occasional tree to rest, but he was panting heavily despite bring the fittest two year old gundog you have seen. It was scary.
Luckily we found a campsite where I went into the bar, ordered myself a drink and asked for water for the dog. (I have to say that the French are brilliant for providing dogs with individual drinking bowls in restaurants). My husband carried on to fetch the car and come back for us. I told him I had poured some of the water over the dog and he said he had read something only a day earlier, which said you aren't supposed to do that.
Luckily all was well, but it shook us up a bit.