I can't tell if my dog has rectal prolapse or a hemorrhoid. How do I tell the difference? She has a protrusion the size of the tip of your pinky that has been slowly growing for months. Part of it is blue/black and the rest is pale pink. She doesn't drag, but does lick. I can assure you she is not constipated; however, she did have surgery to remove much of her intestine when she was young and her bum has pretty much always irritated her.