lab excessive drinking and peeing

Question
Female lab, 15 months old, spayed, drinks an incredible amt of water, almost obsessed with it. She has access to water in house and the minute she goes out, she runs to birdbath to drink some more. Needless to say, she pees all the time and is still is not housebroken! Vet has checked for UTI and diabetes, etc. Could this be a pyschological thing and what should we do? thanks again, Labman

Answer
I think some dogs drink for the sake of drinking, water like food it there to be consumed.  I would limit her to a gallon of water a day, spacing it out through the day including after every meal.  That should still be more than she needs.  Stay in touch with the vet.