Q: Recently, my sterilised cat’s derriere has been very pungent. I thought he might have gotten some poop on himself, but even after bathing him, he smells. The area where his testicles used to be is a tad swollen. Do cats have anal glands like dogs?   

A: Yes, cats do have anal glands. All cats have a pea-sized anal sac that sits on both sides of their anus. These sacs are lined with glands that secrete a smelly, thick, cream-coloured fluid continuously. This secretion is used to lubricate the anus while also acting as a scent marker for delineating territory. Normally, the anal sacs are emptied during defecation due to pressure from the poop as it passes through the rectum and out the anus. It is also released during territorial marking and when there is fear or anxiety. It helps cats to identify each other by smell. This is why cats will sniff the rear end of other felines when they first encounter each other.

Anal sac disease—what your cat probably has—is a common problem in cats. It develops when these anal sacs become inflamed, infected, abscessed, blocked, or impacted with the secretions that should have been released. Studies have shown that cats are prone to developing anal sac impactions, which occur when anal sac secretions build up due to the tube or duct of the anal sac being clogged up.

One of the most common causes of feline anal sac disease is being fed a diet that is too low in fibre. A good diet results in well-formed stools, which, on their way out of the body, push the anal sacs and cause them to release their contents. Soft stools are too mushy to do the same. The moisture in the build-up of secretions will be reabsorbed, but the sebum (the thick part of the secretion) will stay in the sacs, causing it to get increasingly thicker. It can become gooey, pasty, and even hard as time goes by. Anal sac disease can lead to eventual rupture of the anal sacs. Persistent chronic diarrhoea, poor muscle tone, obesity, and lack of exercise can also contribute to impacted anal glands.

An anal sac becomes infected when bacteria builds up in it, leading to inflammation, pain and discomfort. Eventually the sac will swell up significantly to develop into an abscess filled with pus, blood and anal gland secretions. Cats affected with anal sac disease may lick the anal area, scoot or drag their bottom along the floor, bite their tails, or have difficulty with defecation or sitting. If your cat exhibits these signs, you need to bring it to the vet as soon as possible.