2 1/2 yr old german shepherd peeing while walking through the house

Question
My dog Ben will walk through the house and just pees.  He seems to do so without thinking anything about what he is doing. This will happen after we have just taken him out or any time
between times that he goes out.
Why does he do this?
We have had him checked out at the vet and nothing is showing up in his labs.
What can I do to stop this?
My husband has been talking about putting him down due to having to continue to keep up with the cleaning.

Answer
Try a different vet,  If he is peeing without even being conscious of it, there is something wrong.  My dog started that and although there was no blood in the urine, there was thousands of white blood cells in the urine sample.  She had an infection.  Most vets only do the strip test which is not conclusive.  If it is a bladder problem, there are drugs, one is called Proin, that treats incontinence in dogs.  I have one of mine on it and the vet wanted me to give one a day.  I give a half once a week and it solved the problem.
nancy