Heat can be a real problem to all animals and whenever I have a walk or a visit, I always ensure I fill up drinking bowls or carry a mobile water bowl on me for walks.
It's lovely to play in the river with dogs and good to cool them down but I stop them drinking river water where possible as it can carry Weil's disease (from rat urine), read about the symptoms here. Domestic rats are some of my clients but wild Mr Ratty can cause many problems!
Our lovely population of bees and other insects like wasps can sting little paws so I always carry cloths and bottled water in my pack to use in a cold compress to ease the pain. Vets can prescribe an antihistamine, some good advice is here but dogs can be allergic to an ingredient in some so you should always get a vet's advice before administering treating yourself.