What are anal sacs?
The anal sacs are located on either side of the anus at the nine o’clock and three o’clock positions. They are positioned just under the skin and connect to the anus through small canals or ducts. Anal sacs produce and store a dark, foul-smelling fluid. These are similar to the glands a skunk uses to scare away its enemies.
Although dogs can use these for the same purpose, most dogs live in an environment that has no enemies. Because the sacs are rarely emptied, the fluid builds up, solidifies and becomes an ideal environment in which bacteria can grow.
What kinds of problems can occur in the anal sacs?
There are three diseases that occur in the anal sacs:
  • When the fluid becomes thick and solidified, the condition is called impaction.
  • When bacteria grow in the anal glands and produce a yellow or bloody pus, the condition is called infection.
  • When the infection builds to create a hot, tender swelling in the gland, the condition is called an abscess. When the abscessed material overflows the sac, the skin over the sac breaks open and the pus drains onto the skin.
How will I know if my dog is having problems with his/her anal sacs?

Symptoms of anal sac disease are:

  • Scooting or dragging the anal area
  • Excessive licking under the tail
  • Pain near the tail or anus
  • A swollen area on either side of the anus
  • Bloody or sticky drainage on either side of the anus
How are the various anal sac diseases treated?
The treatment for impaction is to express the sacs and clean out the solidified material. For infection, the sacs must be expressed and antibiotics administered to kill the bacteria. If the sacs abscess, the abscess must be surgically drained and antibiotics administered.
My dog has had several bouts of anal sac disease. Is there a long-term cure?
Many dogs have recurrent anal sac disease. Some factors, like breed and weight, can predispose dogs to these problems. If a dog has several episodes of anal sac disease, the anal sacs can be removed surgically. Because these sacs are virtually unused, there is no loss to the dog. It is the only way to permanently cure the problem.
Are there any complications with the surgery?
Surgery requires general anesthesia which always carries some degree of risk, whether the patient is a dog or a person. However, modern anesthetics make this risk very minimal for dogs that are otherwise healthy.
Some dogs will experience a temporary lack of bowel control. This occurs because the nerves that control the anus are very near the anal sacs and may be damaged during surgery. However, this is almost always a temporary problem that will resolve itself in a few days to a couple of weeks.
My dog frequently leaves a foul-smelling drop of liquid on the furniture. Is this related to anal sac disease?
Some dogs are born with anal canals that do not close well. These dogs are constantly draining anal sac fluid and leaving a foul-smelling drop wherever they have been. This is another indication for anal sac removal since there does not appear to be any other way to stop this and dogs do not outgrow this problem.
See Anal Sac Disease in Cats