Am I the only pet owner who's tried to shove a bowl of water under my pup's dangling tongue . . . only to have him turn his nose up at it? I didn't realize that just because his tongue was out,it didn't mean he wanted a drink. Dogs hang their tongues out when they are hot (sometimes they're also thirsty), but it's actually a way to cool themselves off. Typically, and pups pant and breathe in air through their noses and release the air through their mouth - when the mouth's open,the saliva can evaporate, producing a cooling effect! So whether your picky pooch doesn't choose water when he's external, or just know his body's working to further cool down his blood flow just by that cute technique.
Source: popsugar.com