Thank you for contacting Petco Pet Education Center, formerly Petcoach with your question about Butta and for providing a picture, it's very helpful. That looks like it may be an anal prolapse, where a bit of the anus protrudes out. This does need to be checked out by a vet. First thing in the morning, I would take him into the vet. Tonight, just keep n eye on him. I hope this helps!