Q Every few months over the last two years, my 4-year old calico cat has had a problem with impacted anal sacs. Her veterinarians have flushed, irrigated, and infused medication, but the problem seems to keep coming back. Is there anything I can do to prevent future occurrences of this problem?

A Anal sac problems are rare in cats, at least compared to dogs. Anal sacs are pea-sized, saclike structures located under the skin around the anus at about the 4 o'clock and the 8 o'clock position. They reside within the fibers of the anal sphincter muscle (the "pucker" muscle), and they each have a small duct that opens onto the surface of the anus. The lining of the sacs secretes a foul-smelling liquid that is temporarily stored and then expelled out of the openings when the anal sphincter muscles contract or when the anus is stretched during defecation. The exact function of the liquid is not known, but it's believed to serve as a form of olfactory communication with other cats.

Normally, the liquid is thin enough to flow easily out of the duct leading from the sac. But in some cats, the liquid becomes too thick to be expressed, and ultimately the sac becomes distended and uncomfortable. (Alternatively, it's possible that the ducts are too small in some cats, allowing the liquid to build up). A cat with impacted anal sacs will often plop its rear on the floor and scoot in an attempt to relieve the pressure. Left untreated, the sacs can become infected or even rupture, spilling their contents into the surrounding tissues and creating an abscess.

Initial veterinary treatment of anal sac impaction involves expressing the contents of the sac. If the anal sac secretions are too thick to be squeezed out through the duct, veterinarians often find it necessary to flush a liquid - usually saline or an antibacterial medication - into the opening of the duct to soften the contents so they can be expressed. Abscesses need to be treated more aggressively with antibacterial medication, in addition to other methods that encourage drainage.

Cats that have suffered from anal sac impaction may benefit if fed a diet high in fiber. The stools produced by this kind of diet tend to be bulky and, theoretically, place more pressure on the anal sacs during defecation to aid complete emptying.

Frequent veterinary examinations and manual expression of the sacs are helpful as well, since recurrence is common. However, in my experience, cats with more than a few episodes begin to impact with increasing regularity, and medical management becomes increasingly difficult. Surgical removal of the sacs is the best course in these cases. The surgery is neither particularly difficult nor lengthy (however, make sure to discuss all the pros and cons with your veterinarian), and it allows these cats to lead a normal life.