Anal sacs are small paired pockets located between the internal and external anal sphincter muscles, one on each side of the anus at the 4 and 8 o’clock position. The sac empties through a short and narrow duct to the surface near the inside edge of the anus. Each sac is lined with (oil) glands and numerous (sweat) glands. The secreted substance is a semi-oily, brownish fluid that packs strong fishy odor.
some dogs' anal sacs produce a rather thick, semi-solid material which is much more prone to impacting the sac due to the sacs' inability to pass this semi-solid material through the narrow duct to the outside.Some cats have difficulty passing it with the stool due to over weight. In many of these cases the sac will become infected, cause pain and inflammation and even break through to the skin surface.
The abscessed anal sac may need surgery to provide drainage and treatment of the damaged and infected sac and surrounding tissue. Antibiotics are indicated in abscessed anal sac disease.
Routine anal glands expression every 3 months as a preventive measure.