Sadie, the beagle who we had in the years before we got Astrid, lived to be 16. She 'leaked' for the last few years of her life. It only happened when she was in one spot for a very long period of time like during the night, or on a beautiful day when she went out and sat in one spot for several hours. I've heard that they have a drug that the vet can perscribe to help with the problem. My guess is that is is similiar to what they advertise on TV for humans with similiar problems. I preferred the natural route and just really kept on top of cleaning her favorite areas. The 'onboard' attachments really got a workout on my steam carpet cleaner over those years. 

Is there another male dog in the house right now?  Not all dogs do this, but my male dogs for some reason mark their territory.  It never happened when there was only one male dog in the house.  Only since we've had 2 males.