drinking water

[susieq8163]

I have a 12 yr old lab who drinks excessive amount of water, so much his stomach gets bloated like he ate a big meal. He has paralized trachea so his air supply at this time is fine, nice pink gums but with his drinking his abilites to breathing could be comprised. I have a little stream that goes through my yard due to all the rain, he was drinking water and I went back to feeding my horses and he walked over near me and he seemed to be breathing very hard and he fell over, i ran over and massaged him and taped his chest and he started to breath better and soon was up like nothing happened. I have had blood test and urine sample done(urine very deluted) all his test for being a diabetic and kidney function and bunch much stuff and xrays showed nothing. anyone have this problems with a dog? any ideas what else i should check for?