[header] How to diagnose canine anal sac problems [title] Locate your dog's anal sacs. [step] Look for two sacs on either side of your dog's anus, at the " twenty past eight " position on a clock face. The sacs should each be the size of a small grape and sit just underneath the skin. 
[substeps] Your dog's anal sacs drain out onto his feces through small ducts. When your dog needs to toilet, the squeezing action forces a few drops of the smelly secretion out of the sacs and onto each bowel movement.