Additionally, a dog's internal temperature can also be a sign. If it's above 105 then stop, cool and then hydrate. One thing you don't want to do if you think your dog is overheating or dehydrated is to wet them down or swim them and then stick them in a dog box or kennel. Evaporative cooling is the most effective way to cool down a dog, but putting a wet dog in a hot box or kennel only turns that space into a humid sauna. Instead, stake out or your dog in the shade where he can get some airflow for good cooling, or better yet, throw them into the cab of your truck and crank the A/C.