The anal glands can actually get plugged and even abcess to the outside of the body. If the areas you are seeing are just below and to one side of the actual anus - it may be the anal glands. If this is the right location - warm compresses a three or four times a day seem to help as well as epson salt soaks can help. It is likely though that if it does seem like an anal gland abscess that he may need antibiotics. If this seems to fit, adding fiber to the diet can help them to clean the anal glands with bowel movements. Canned pumpkin added to the diet is often recommended to add fiber to the diet in a very palatable way. Here are some links to more information about anal glands.
Other reasons for growths in the area, licking and discomfort are anal fistulas and perianal adenomas. Male dogs that are not neutered also tend to get tumors around the anus tha seem to decrease if they are neutered. Here are some links to more information about these conditions.
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