Always check with your vet. it could have been a distended anus and that can be very SERIOUS!!!! We had to put a little lab puppy down the other day due to that very problem. The lady took him to another vet and had him operated on TWICE and still it turned out that we could not save this beautiful little pup, it had gone too far to help him and apparently the other vet didn't really know what he was doing. She kept taking him back and the vet told her she was over-reacting! Can you belive that?????? And now her baby is dead, so always check with a vet that you trust to tell you the truth!!!!!!!