answer:I found this on Goolge for you; I hope it helps. It seems this could be occurring for a number of possible reasons. Such as: Anal Gland Issues Intestinal Parasites External Parasites and Allergies Skin Infections Grooming Anxiety In short, because this could be any of those issues (or a combination of them), I would suggest consulting with a veterinarian. Obviously if it is just a grooming routine, that is nothing to worry about. Get it checked out, in either case.