Anal sac disease in cats (impaction, inflammation, abscess)
Cats have two small pouches on either side of the anus called anal sacs. These sacs produce a strongly scented fluid that normally empties when the cat passes stool and is used for scent marking. When this fluid no longer drains properly, t...
What is it?
Cats have two small pouches on either side of the anus called anal sacs. These sacs produce a strongly scented fluid that normally empties when the cat passes stool and is used for scent marking.
When this fluid no longer drains properly, the pouch fills and becomes blocked—this is impaction, the most common form. The pouch may then become inflamed, then infected and develop an abscess that sometimes ruptures near the anus.
These problems are uncommon in cats, far less frequent than in dogs.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The cat drags its rear end along the floor.
It licks or nibbles at the anus area or beneath the tail persistently.
The area beside the anus is red or swollen; a lump may appear on one side.
A strong and unusual odor comes from the rear end.
If an abscess has ruptured: a small wound leaking beside the anus, with brownish, bloody, or purulent fluid.
Straining or pain when defecating, sometimes with fecal retention and constipation.
Fever and lethargy may occur with an abscess.
To distinguish: in a rectal prolapse, it is the anus itself that protrudes at the center; here, the lump or wound is to the side.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Poor drainage of the sacs, for example when stools are too soft for a prolonged period and no longer compress the pouches as they pass.
Abnormally thick anal sac fluid.
Inflammation of the skin in the area.
Bacterial infection that turns an impaction into an abscess.
In many cases in cats, no specific cause is found.
This condition is rare in cats; its predisposing factors are poorly documented in this species.
Prolonged soft stools are often mentioned, though this link has not been established in cats.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The vet examines the anal region and palpates the anal sacs, sometimes with gentle rectal palpation.
They assess the appearance of the fluid expressed: thick, bloody, or purulent.
They distinguish anal sac disease from other causes of anal discomfort: worms such as tapeworms, irritation from chronic diarrhea, rectal prolapse, tumour, or bite wound.
If an abscess is present, they evaluate the extent of infection and check for fever.
Treatment
An impacted sac is emptied by the vet, sometimes under sedation if the area is very painful.
If inflammation or infection is present, the sacs may be flushed and local or systemic treatment prescribed: anti-inflammatory, antibiotic depending on the case.
An abscess is opened, cleaned and treated; it usually heals well.
The underlying cause is treated, particularly if diarrhea is prolonged.
If recurrence is frequent, surgical removal of the anal sacs may be recommended.
Do not attempt to lance or empty a swelling near the anus yourself: the area is painful and improper handling worsens infection.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There is no specific preventive measure.
Prompt treatment of diarrhea that persists limits the risk of anal sac impaction.
Watch the area around the anus during petting or brushing, especially in long-haired cats.
A cat that scoots or licks the anus constantly should be examined.
Possible complications
Abscess rupturing beside the anus.
Recurrent impaction or infection.
Constipation because the cat refrains from defecating due to pain.
Scars or fistulas when infection persists untreated.
When to see a veterinarian
You see a painful swelling or a draining wound beside the anus: consult the same day.
Your cat has fever, is lethargic and shows a swelling near the anus: consult the same day.
The cat scoots or licks the anus persistently.
It experiences pain or strains excessively during defecation.
In a male, straining in the litter box without producing anything may indicate urinary obstruction: seek immediate help.
Prognosis
The prognosis is good: most anal sac impactions and abscesses heal well with appropriate treatment.
Recurrence can occur; it is managed by treating the underlying cause or, if recurrent, by surgery.
Frequently asked questions
My cat is dragging its rear end: anal glands or worms?
Both are possible. If you see small white grains like rice around the anus or on its bedding, these are likely tapeworm segments, often causing little pain. A lump, redness, or a weeping sore next to the anus points more toward anal gland issues.
What is the difference with a rectal prolapse?
In a prolapse, it is a red mass that protrudes from the center, through the anus itself. In an anal sac condition, the swelling or wound is located to the side of the anus.
Should you regularly empty your cat's anal glands?
No, in a cat that has never had a problem. A gland expression is only useful if the veterinarian detects impaction, and any necessary frequency should be decided with them.
Is a wound near the anus an emergency?
It is often an abscess that has burst. It is generally not a life-threatening emergency, but you should see a doctor within the day to clean the wound and treat the infection.
References
Content reviewed by the TunisieVet editorial team · Updated 11 October 2026
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