There are several different reasons dogs lose water from their body. A few ways this can happen is through panting, urinating, and evaporation through the feet and other body surfaces. Obviously, dogs replenish their fluids by drinking water or other liquids, and also by eating moist foods. Even a relatively small drop in their water content such as four to five percent, could result in signs of dehydration. Maintaining a constant fluid content is as important in dogs as it is for humans.
Your dog’s skin will lose elasticity as it loses it’s moisture. Younger, fatter dogs will have more elasticity than older, thinner dogs. Because of this, it is important to know what your dog’s skin looks and feels like on a normal basis. When you pinch the skin of your dogs back between your thumb and forefinger, it should return to normal immediately. As the tissue loses it’s moisture, it will move back slower, and in some extreme cases, it won’t move back at all.
Another way to check if your dog is dehydrated would be to pull up your dog’s lip and look at their gums. Put your index finger firmly against the gums so they appear white. When you remove your finger, take a look at how quickly the blood returns to the gums. They will become pink in that area again. This is called capillary refill time. If you do this when your dog is completely hydrated, you will have a basis to compare with. The gums of a healthy, hydrated dog will refill immediately, while the gums of a dehydrated dog could take 3 seconds or so to return to their normal state.