Has she been neutered? We had the same problem with Scout, my parent's 10 year old Lab/Retriever mix. Their bladder apparently gets weak as they get older (just like us girls). She now takes hormones of some kind twice a week to control it. She would just be lying there and wet the floor. I had a similar problem with Honey and it turned out to be a bladder infection. She had been boarded for several days and doesn't like to go in the pen. She just held it to long and then she couldn't stop going. Both of these problems have been solved with medication. I sure hope you can get yours worked out. I sure would go back to the veterinarian and if you don't get satisfaction, find another one!