Sleep pooping?

A coworker's dalmation has started pooping in her sleep recently. Ginger is five years old and still has anal tone and good reflexes, so the vet is a bit stumped. My GSD had spinal degeneration and was unaware she was going. Ginger knows when she is awake but sometimes goes in her sleep without waking at all. Ideas?

One of my parents dogs sleep poops, like when I wake up I will find a a bit of poop on her bed, I know she isn't doing it on purpose because I don't hear her moving around at night or anything. It's not all the time either.

Not much information, but at that age it is unexpected to have a problem like that. If the dog is eliminating ok through the day it must be some type of nerve damage. The owner may have to go to a nerve specialist to check it out. Tell the owner that at that age there must be a physical problem of some kind and to persist in finding the cause.