dog drinking alot

[Alaskan]

I have a four and a half year old male rottweiler that in the last year or so has been drinking so much he swells up afterward. He can drink five to seven quarts a day of water and then spends the rest peeing. It isn't hot out he does this even in the winter. We took him to two different vet hospitals and they ran a cbc. did other blood work, urinalysis, and said that he didn't hav diabetes as well as his kidneys looking fine. I'm going to have him checked for cushings syndrome this month. I wasn't sure if they checked his liver though now that I think of it. He doesn't stay bloated though all day and he eats about six measuring cups of Iams adult maitence dry dog food a day and that just keeps him at 90-95lbs. Can anyone think of anything else that might be wrong here. I can't let him in the house for to long because he pees so much. Any info would be appreciated in which I could talk with the vet on for further tests.

[MARYDVM]

Aside from checking out Cushing's disease, your vet may want to pursue the possibility of diabetes insipidus. This is not the "sugar" diabetes most people are familiar with(diabetes mellitus).Diabetes Insipidus can result from an absence of the hormone that stimulates the kidney to concentrate urine(ADH or antidiuretic hormone). With Diabetes Insipidus you can have normal blood values with the only lab abnormality being dilute urine(low specific gravity). This can be hard to diagnose, there are a couple of ways to test for it. You may need to see an internal medicine specialist.

[Alaskan]

Thank you and I will discuss this with the vet too. I haven't heard of the other type of diabetes before but will be sure to mention it.