There are all kinds. It just depends on how much stuff you want to carry.

1. Cool Pooch Water Bottle

2. Thirsty Dog

3. Handy Drink

4. Or how about a Gatorade or Propel water bottle with the twist top?:


Personally, I use number 4. Squirt some in his mouth, away we go. Keep a jug to refill your bottle in the truck.

Enjoy.