My 12 week old lab mix left two half dollar sized puddles during puppy school last week and the trainer said that he was overhydrated. I have a full bowl of water out for my older dog who has learned to self-regulate, but the puppy drinks like he's just finished a crawl through the desert. I thought I was already doing a good job monitoring his water intake, but now I'm not sure. The day of training, he hadn't had anything to eat or drink for almost 5 hours before the class. How do you know how much water is enough? It's been really hot, and I'm afraid of letting him get dehydrated.