We have a Boston Terrier that used to sleep with us. When she was a puppy she wet the bed probably at least 5 or 6 times. Wouldn't budge in her sleep at all. Never knew what happened till morning. Thank goodness we had a waterproof mattress pad. She has since outgrown it.
It was crazy-she was just like a child bed wetter I guess. She is my husbands dog and normally would lay at the foot of his side under the covers. Lucky him.