All Feline Hospital

2300 S. 48th St. Ste. 3
Lincoln, NE 68506


Impacted Anal Sacs

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Cats have two anal sacs on either side of their anus that sit right around 4 and 8 o'clock.  These sacs have multiple oil glands that empty into them continuously.   The oil that these sacs fill up with is very potent smelling, and helps cats to identify each other by smell.

When your cat defecates, these sacs are expressed onto your cat's stool as another way for your cat to mark their territory.

This is also why cats will sniff the rear end of other cats when they first meet - they are sniffing the anal sacs to be able to identify the other cat by their smell.



If your cat's stools, for any reason, are either too small or too soft to push on the anal sacs, this can result in the sacs failing to empty during defecation.

If the sacs are not emptied with each defecation, then the oil will continue to build up.  The moisture in the oil will be reabsorbed into the body, but the sebum, the thick part of the oil will stay in the sacs and will get thicker and thicker as the moisture is reabsorbed.

Over time the oil becomes so thick that your cat cannot physically empty their anal sacs even if they have a normal stool.

Eventually, if these sacs are not emptied, they can rupture which results in a smelly abscess on your cat's rear end.



Most cats will not show symptoms of impacted anal sacs until they are close to rupturing, or have already ruptured.  A few symptoms you might see are:

  • Scooting.  This is when your cat drags their rear end across the floor.
  • Excessive licking at the rear end.
  • A foul smell or discharge from the rear end.



If we find the impacted anal sacs before they rupture, we will manually express them so that they can function normally again.

If the anal sacs have already ruptured, we will treat with antibiotics, an e-collar to keep your cat from licking excessively at them, and possibly surgery if the abscess is too large to heal on its own.



The most effective prevention is to keep your cat's stools normal and large enough to push on the anal sacs during defecation.

  • One way to do this is to give your cat supplemental fiber - either 1 tablespoon of canned pumpkin or 1 teaspoon of Benefiber mixed in moist food daily to bulk up your cat's stools.
  • A hairball diet which contains higher levels of fiber may also help bulk up your cat's stools.
  • The only exception to using fiber would be if your cat had megacolon or end stage constipation issues - both of which can be complicated by fiber.

If your cat has abnormal stools due to another disease process, if we can treat that disease process, then we may be able to prevent the anal sacs from failing to express normally.

If we are unable to give your cat fiber or treat an underlying disease process to result in normal stools, then we may recommend having your cat's anal sacs checked every 3-6 months to minimize the risk of rupturing.


If you are not sure if your cat's anal sacs are becoming impacted, please bring your cat into see us and we can examine them to find out, and express them if they are full to prevent rupture.


If you have any questions on any of the above, please contact us at All Feline Hospital at 402-467-2711 or


This handout was written by Dr. Shelley Knudsen, DVM



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