When I think of anal gland problems, I usually think of dogs, and there’s a good reason for this: Dogs are much more likely to have blockages and other issues with those little sacs than cats are. But, as I learned last week, cats can also suffer from blocked anal glands.

When I brought Siouxsie in for her three-month post-radioactive iodine therapy checkup, my vet noticed something odd: One of her little sacs was swollen to the size of a marble. Needless to say, we got that taken care of right away. “Better them than me,” I said as one of the techs brought Siouxsie back to the treatment room.

So, just what are the anal glands and what do they do? Here are some answers.

1. They’re not actually glands, they’re sacs

The anal sacs are lined with glands that produce an oily and stinky substance. If you look at your cat’s butt, you may be able to see the outlets of the anal sacs at about four and eight o’clock in relation to the anus.

2. In wildcats, anal gland secretions are used to mark territory

When a wildcat poops, the passage of feces through the anal canal squeezes the anal glands and expresses a little bit of that strong-smelling fluid. This serves as an extra tool for marking the boundaries of that cat’s range. In domestic cats, the anal sacs are considered vestigial, although they do seem to play a large role in cat social dynamics.

3. That butt sniffing thing? It’s all about the anal sacs

The secretions from the anal glands are part of the unique smell that identifies individual cats. This is why cats often greet one another with mutual butt sniffs.

4. The glands can get impacted

If the oily substance plugs the opening of the anal sacs, the secretions build up inside and can cause pain and discomfort. In cats, the anal sacs are probably about the size of pine nuts, but they can grow to several times that size when the openings are clogged.

5. Cats don’t show symptoms like dogs do

When dogs get impacted anal glands, they tend to scoot their butts along the floor and lick the area excessively. Cats, with their legendary ability to hide their pain, just bear the discomfort. If you don’t see a problem, this can result in serious problems.

6. Obesity can contribute to anal sac problems

Some vets say that anal sac impactions are more common in overweight and inactive cats, perhaps because obese kitties can’t clean their bottoms as well as their leaner kin, and a lack of exercise could lead to constipation. Constipated cats don’t have frequent enough bowel movements, and this may cause the secretions to plug the gland openings.

7. Untreated, impacted glands can rupture

If you thought anal sac secretions were gross, just wait until the glands abscess and rupture. Not only is this incredibly painful for the cat, it’s also very inconvenient for the owner, who ends up having to rinse out the affected gland every day and cope with a cat who has to live in a cone collar for a week or so.

In healthy cats, the anal sacs quietly go about their business and don’t cause any harm. But, as I learned with Siouxsie, sometimes elder kitties have a harder time taking care of their business back there and this can result in impaction. In cats with chronic anal gland problems, vets may recommend surgery to remove the glands.

Have you ever had a cat with impacted anal glands? Do you have any tips for us so we can see the signs before the problem becomes critical? Do you have any other comments about our feline friends’ anal sacs? Please share them in the comments.

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About JaneA Kelley: Punk-rock cat mom, science nerd, animal shelter volunteer and all-around geek with a passion for bad puns, intelligent conversation, and role-play adventure games. She gratefully and gracefully accepts her status as chief cat slave for her family of feline bloggers, who have been writing their award-winning cat advice blog, Paws and Effect, since 2003.