Experts believe that dogs in the wild use the anal sac secretions to mark their territory, or as a defensive repellent against aggressors. When domestic dogs are frightened or upset they may also eject some anal sac secretion. And since each dog's anal glands produce a unique scent, dogs are able to identify other dogs by sniffing their stools or their rear ends.

When dogs' anal sacs are not emptied properly during defecation they can become impacted. Impaction can be caused by soft stools, overactive anal glands, or small or clogged anal ducts. The pressure from the impacted sacs can cause your dog to scoot his rear end along the ground, lick the anal area excessively, or exhibit unusual behavior such as anxiety or pacing. Because these symptoms can also be signs of other problems, such as worm infestation or skin infection, your dog should be examined by your vet.

A dog's anal sacs may also become infected, or may abscess or rupture. Infected anal sacs can be very painful. As well as scooting and licking, the dog may cry during defecation, and when it is touched in the area near the tail. There may also be blood or pus in the anal gland secretion.

Whereas anal sac infections, abscesses and ruptures must be treated with antibiotics, surgical treatment or even removal of the glands, anal sac impaction is relatively simple to correct. The anal sacs must be cleaned out, or "expressed". As this is quite an easy process, owner/guardians can do it themselves, if they are taught how to do it and if they choose to perform it.

Some experts consider anal sac problems a disease of modern living, caused primarily by the change to commercially-produced dog food. If frequent anal sac impaction occurs in your pet you should speak to your veterinarian.