HOW TO PERFORM A DEHYDRATION TEST ON YOUR DOG

​Lift one or two inches lightly on the skin between the dog's shoulder blades if it doesn't return quickly to the original position, your dog is potentially experiencing dehydration.
Another method for testing dehydration is to check your dog's gums first lift your dog's lip and look at the color of the gums. Press the gums with your index finger so that it appears white. Release your finger and watch how quickly the color returns. The gums of a normal dog refill immediately. Gums of dehydrated dogs could take up to three seconds to refill.
Call your veterinarian if your dog shows signs of shock, heat stroke, or severe dehydration. 
Offer your dog small sips of water every few minutes. You can also mix electrolyte replacement powder with the water or pieces of ice to lick. Too much water too quickly could cause the dog to vomit.