Excessive thirst in Dog
Increased thirst of your dog

There are several natural reasons dogs get excessive thirsty. On a hot day dogs pant to keep themselves cool; doing this makes them get rid of the humidity in their lungs through evaporation. So obviously, don't get alarmed if your dog is thirstier than normal on a humid hot day since, just like humans, dogs need to recuperate the lost water in their bodies and even more so for dogs with big thick coats. For this reason, it's very important to avoid leaving your dog locked up in the car when it's hot because dogs get dehydrated quicker than you would imagine. A dog that has done vigorous exercise, or a dog that is pregnant or feeding her little puppies obviously needs more water than normal too. Sometimes something as simple as a change in a dogs diet can make a dog feel more thirsty than normal. Canned dog food can contain up to 80% of water in them, whereas dog biscuits or dry dog food only has about 8% of water. Some dog foods are made saltier than others to enhance the flavor, and this will also logically make the dog thirsty. Whatever the case, it's important that you let your dog drink as much water as he wants (unless your veterinarian tells you the contrary because of a health problem). Not providing free access to fresh clean water to a dog could cause him to have serious health problems.