How soon after eating something sharp do you need to start feeding the cotton balls?  Last night my dog, Ohana, got into the recycle bin.  All that had been in there were a couple of (rinsed out!) empty cans of soft cat food.  I didn't think anything of it then, but I woke up this morning with the thought that I bet she ate one of those cans - there really should have been one more than what I picked up last night.  She had a sinlge bout of diarrhea late last night and her belly feels a little distended, but otherwise she isn't acting like she's in pain.  It's been like 12 hours since she may have eaten the can - probably too late to feed cotton balls.  How long does it generally take for something to pass through a dog's system?  If all of her stools are normal today, can I quit worrying?