Stan Wood, DVM, Diplomate ABVP

Specialist in Canine & Feline Practice

Anal Sac Disease in the Dog

The anal sacs are located on either side of the anus at the 9:00 and 3:00 positions; they are positioned just under the skin. They connect to the anus by means of small canals, or ducts. Anal sacs produce and store a dark, foul-smelling fluid. These are the same types of organs that a skunk has to scare away its enemies. Although dogs can use these for the same purpose, most dogs live in an environment that has no enemies. Because the sacs are rarely emptied, the fluid builds up, solidifies, and becomes an ideal environment in which bacteria can grow.

Prevalence

The prevalence is higher in smaller breeds of dogs.

Causes

There are 3 diseases that occur in the anal sacs.

1) When the fluid becomes thick and solidified, the condition is called impaction.

2) When bacteria grow in this material producing a yellow or bloody pus, the condition is called infection.

3) When the infection builds to create a hot, tender swelling in the gland, the condition is called an abscess. When the abscessed material overflows the sac, the skin over the sac breaks open, and the pus drains onto the skin.

Clinical Signs

Symptoms of anal sac disease are:

Scooting or dragging the anal area

Excessive licking under the tail

Pain, sometimes severe, near the tail or anus

A swollen area on either side of the anus

Bloody or sticky drainage on either side of the anus

Diagnosis

Physical examination, including a rectal examination, will usually confirm the diagnosis.

Treatment

The treatment for impaction is to express the sacs and clean out the solidified material. For infection, the sacs must be expressed and antibiotics administered to kill the bacteria. If the sacs abscess, the abscess must be surgically drained and antibiotics administered.

Some dogs are born with anal canals that do not close well. These dogs are constantly draining anal sac fluid and leaving a foul-smelling drop wherever they have been. This is another indication for anal sac removal. There does not appear to be any other way to stop this, and these dogs usually do not outgrow this problem.

Prognosis

Many dogs have recurrent anal sac disease. Some breeds of dogs, such as Poodles, commonly have problems. The anal sacs of obese dogs do not drain well and, thus, these dogs are predisposed to recurrent problems. If a dog has several episodes of anal sac disease, the anal sacs can be removed surgically. Because these sacs are virtually unused, there is no loss to the dog. It is the only way to permanently cure the problem.