Anal Sac Disease in Cats

The anal sacs are located on either side of the anus just under the skin at the four o ’clock and eight o’clock positions. They connect to the anus by means of small canals called ducts. Anal sacs produce and store a dark, foul-smelling fluid. These are the same types of organs that a skunk has to scare away its enemies and mark its territory. Although cats can use their anal sacs for the same purpose, most domestic cats have no need to mark territory or repel predators. A small amount of anal fluid is usually squeezed out by muscular contractions whenever the cat passes a bowel movement.

What diseases occur in the anal sacs?
There are three diseases that occur in the anal sacs.

  1. When the fluid becomes thick and solidified, the condition is called anal sac impaction.
  2. When bacteria grow in this material producing yellow or bloody pus, the condition is called anal sac infection.
  3. When the infection gets trapped within the sac, often because the duct has become obstructed, it will create a hot, tender swelling, leading to a condition called an anal sac abscess. The pressure in the sac builds up until eventually the skin over the sac breaks open, and the pus drains out, causing an anal sac rupture.

What are the clinical signs of anal sac diseease?
Symptoms of anal sac disease most commonly include:

  • Scooting or dragging the anal area along the ground.
  • Excessive licking under the tail.
  • Pain in the area of the anus.
  • A swollen area on either side of the anus.
  • Bloody or sticky discharges on either side of the anus.

How are these 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.

How likely is it for anal sac disease to occur again? 
It is not very common for cats to have recurrent anal sac disease. But it can happen. To try to prevent reoccurrence, we recommend coming in for anal gland expression (emptying) every 3-4 months.
Some overweight cats will have chronic anal sac problems. The anal sacs of obese cats do not drain well, thus these cats are predisposed to recurrent problems. If a cat has several episodes of anal sac disease, the anal sacs can be removed surgically. Because these sacs are not necessary, there is no loss to the cat. It is the only way to permanently cure the problem.

Are there any common surgical complications?
Surgery requires general anesthesia, which always carries some degree of risk, whether the patient is a cat or a person. However, modern anesthetics make this risk minimal for cats that are otherwise healthy.
Some cats will experience lack of bowel control after the surgery. They may drop fecal balls as they walk. This occurs because the nerves that control the muscles surrounding the anus are located near the anal sacs and may be damaged during surgery. In most cases, this is a temporary problem that will resolve a few days to a few weeks after surgery.

Can anything else happen to anal sacs?
Some cats are born with anal canals that do not close well. These cats are constantly draining anal sac fluid, leaving a foul-smelling discharge wherever they have sat. This problem is not outgrown, and the only effective treatment is surgical removal of the anal sacs.