If you would like a separate list of what to put in your own dog first aid kit, ask us for the list. Depending upon trail conditions, take dog boots with you to protect your dog's feet from damage. You should have a small can of Bag Balm for your dog's feet in your dog first aid kit or each dog's pack. If your dog is hot, drinking cold water could cause regurgitation. If it laps up water to quickly, it can choke.
Water is important for evaporative body cooling in dogs.
Insure it is offered water frequently. This also helps cut the desire to consume trailside water that might be contaminated. Wetting his feet helps to cool his entire body. Remember that your dog can suffer from mosquitoes, ticks, chiggers, flys, etc. Make sure you are using some kind of repellant.