Dog urinating on our bed

Question
The other day we discovered that my 6 year old female beagle had urinated on my husbands side of our bed.  There was so much urine, that it went through a comforter, blanket, sheets, matress pad, and well into the mattress.  Then last night when tucking my 5 year old in, we noticed that she peed on her comforter.  Tonight, we had gone out just long enough to pick up my daughter at a birthday party and when I came upstairs, I found that she has urinated again on my husbands side of the bed.  She went through peeing on the floor last year, and we took her to the vet who couldn't really find any reason, but I'm wondering what could be the cause of this.  This is terrible!  Any help you could provide would be appreciated.

Answer
Hi Jen. WEll this question is easy on my end. On your end, you may not like what i have to say. This dog is very smart. She is playing the dominant position over all of you. You need serious dog training from a good dog trainer. Please look them up at the BBB and check references.

Good luck
Nancy