IF it is DI, we are not talking about a little bit more water than normal, we are talking EXCESSIVE. Every new puppy owner feels like all they do is take their dog outside to pee, so they tell you it's normal. With DI, all your puppy wants to do it drink until they almost explode, and they pee every 5 minutes. it's not normal.
Loki was born with DI. His body just doesn't make vasopressin. Most vets are unfamiliar with it because it is extremely rare. Loki is almost 6 and does very well on medication. If your vet thinks it could be DI (clear pee, excessive drinking - sounds like it's possible to me) then the only test for it is a water depravation test which you DO NOT want to do. The better alternative is to simply get the medication and use it and see if there is an improvement (they will do urine specific gravity tests before and after).
The most difficult part of it all is the cost of the medication. You give it twice a day as an eye drop, pill or injection. Lately it's been hard to find. You also probably will never be able to just leave him home for 8 hours (not that most Yorkie owners can) I guess you could pee-pad train him, but you'll be setting out 5 or 6 pee pads at a time to absorb it all. Even with meds Loki goes an excessive amount - he's outside anywhere from every 45 mins when he's active to every 2-3 hours in between naps. Yes I can leave him home for 4-5 hours and he will nap and he does sleep through the night now, but I had to make sure he's medicated, leave water out, and MAKE SURE that he's empty before I leave. I couldn't do this when he was a puppy but he's house trained, medicated and lazy, so I know he will sleep
