On long walks, especially in hot weather, it's wise to take along a collapsible water bowl or a pet water bottle. If it's sunny, apply a sunscreen formulated for pets to the ears, the muzzle, and other areas where skin is exposed; light-colored and light-coated dogs are particularly prone to sunburn. If insects prey on your dog, use a pet-specific repellent (ones made for humans are toxic to dogs). And don't forget treats if you're leash-training.
Keep your pup well hydrated with this foldable silicone bowl. Tazlab bowl, tazlab.com.