Dogs have 2 anal sacs located on either side of the anus.
Anal sacs in dogs are similar to the scent glands of skunks. While skunks use their scent for defense, dogs mark their territory when defecating with secretions from the anal sacs.
There is a strong odor emitted from the sacs. When dogs smell each other’s rears in greeting, they are gathering information about each other. The anal sacs are sometimes emptied if the dog is upset about something.
Impaction occurs when the anal sacs are not completely emptied. Impaction is seen mainly in overweight or small dogs. It can be caused by loose stool, not enough pressure while defecating or a blockage.
If not treated, the anal sacs can become infected leading to abscesses and rupture.
Treatment involves manually expressing the anal sacs. Your veterinarian can best demonstrate how this is done.
If there is sign of swelling, infection or abscess, your dog needs to see the veterinarian. Abscesses may need to be lanced and along with infections, treated with antibiotics. Your vet will advise you as to home treatment.
If your dog has recurring anal sac infections, the sacs may need to be removed surgically. Your vet will advise you if this is necessary.