If you take your dog, take water for the dog as well as yourself. More so, in fact, since they can only cool down by evaporation from panting, which means they lose a lot of water as they cool.
for longer trips I used to freeze the water bladders in Snoop's (my dog) Ruffwear pack. There was one down each off his sides, so as they melted they kept him cold he also had plenty of water as well as drinking from rivers. Also a folding bowl or Pet drink bottle can be handy.