The anal sacs are two pockets either side of the anus in both dogs and cats, they open via a narrow duct just inside the anus and they produce a very strongly smelling substance that is usually squeezed out onto the faeces when a stool is passed. This is part of the territory marking of these species and is perfectly normal.

Problems with the anal sacs, or a suspicion of a problem with the anal sacs is a common reason for dogs in particular but also occasionally cats to be presented at the veterinary surgery.

Causes

Typical causes of anal sacs include:

Impaction or blockage of the anal sac ducts causing the sacs to overfill and become uncomfortable.

Anal sac inflammation or infection of the anal sac

Anal sac abscess, a particularly uncomfortable form of infection.

Cancer of the anal sac, a much rarer problem than blockage or infection.

Signs

Any problem with one or both anal sacs will often produce the same range of symptoms.

Rubbing the bottom on the ground (often called scooting).

Trying to lick or nibble the area.

Swelling around the bottom and possibly some redness.

A particularly bad smell from under the tail, often described as “fishy”.

They may leave a smelly mark on carpets or furniture when they sit down.

They may be reluctant for you to lift the tail or try to examine the area.

If they have an anal sac abscess that bursts you may see a bloody discharge under the tail and a small weeping hole at 4 or 7 o'clock at the side of the bottom. 

They may strain more to go to the toilet.

They may actually be less willing to jump.

If your pet exhibits these signs then it is not likely to be an emergency but you should get them checked by a vet.

Treatment

Treatment may include someone emptying the glands manually or, if infected, they may require flushing and treatment with antiseptic washes and antibiotic infusions. This may require sedation or general anaesthesia.

An abscess, if it hasn’t burst naturally, may require lancing (popping with a scalpel) to drain the infection, again under sedation or general anaesthesia.

Some infections may require a course of antibiotics or repeat treatments to clear them completely.

Poor response to treatment or frequent recurrence of signs

Some skin conditions, particularly allergic skin disease can create and intense itch in what is called the “peri anal area”, that is the skin around the bottom under the tail. This itchiness can produce signs identical to anal sac problems.

If your pet shows repeated signs of anal sac problems after treatment or doesn’t respond to treatment skin conditions should be considered.

Prevention

Anal sac removal

In rare cases where your veterinary surgeon feels that recurrent issues are likely to be related to on going anal sac disease surgical removal of the anal sacs may be considered. There are risks associated with this procedure. Your vet is best placed to advise if your pet might benefit from surgery after considering all the evidence.