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Anal Sac Disease

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ANAL SAC DISEASE

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What are the anal sacs?

Also called “anal glands,” these are two small pouches located on either side of the anus at approximately the 4 and 8 o’clock positions. The sacs are lined with numerous specialized sebaceous (skin) glands that produce a foul smelling secretion. Each sac is connected to the outside by a small duct which opens just inside the anus. These are the same glands that skunks use to spray musk. In dogs the smell is not as pungent but it is still bad and can linger for quite some time. We have odor eliminating sprays to help with the smell if you need them.

What is their function?

Anal gland secretion acts as a territorial marker – a dog’s ‘calling card’. The glands are present in both male and female dogs. Normally they empty when the dog defecates. This is why dogs are so interested in one another’s feces.

In cats, the anal sacs are less important for territorial marking, so owners rarely notice any anal gland smell. Cats are also less prone to anal gland problems, though we do see it a few times a year. 

My dog is very nervous and sometimes seems to express his own glands. Is this normal?

It is common for dogs and cats to express their anal sacs if frightened. Some pets appear to lack control of the anus or anal sac ducts so that small quantities of fluid will drain out when they are resting. This, of course, leaves an unpleasant lingering odor in the home. Sometimes we can cauterize the sac to reduce the amount of secretion produced. In the worst cases we can consider surgery to remove the sac(s). 

Why do they cause problems? 

Diseases of the anal glands include:

1. Impaction -- normal secretions are thick and cannot escape.

2. Infection -- bacteria trapped within the gland produce a yellow or bloody pus. 

3. Abscessation -- as a result of infection, a hot, tender, red swelling, or abscess, forms near the anus.  It may burst and drain bloody pus.


Anal gland disease is very common in dogs. The sacs frequently become impacted, usually due either to the secretions being too thick or to narrowing of the ducts. The thicker and harder the secretions or the more full and stretched the anal glands become the more painful it is for your dog to pass feces. Cat anal sac secretion is almost always fairly thick but cats tend to have less problems with impaction.

The secreted material within the anal sacs forms an ideal medium on which germs can multiply and cause infection. If the anal sac is not emptied out (“expressed”) and pus is trapped inside an abscess forms. An impacted anal gland can become an abscess within just a few days.

If you see a red, angry swelling on one or both sides of the anus, the sac is probably abscessed. The abscess may burst, releasing green, yellow or bloody pus. If untreated, the infection can quickly spread to surrounding tissue and cause damage to the anus and rectum.

Infected anal sac(s) are more painful than impacted ones. Even normally gentle dogs or cats may snap or growl if you touch the tail or anus when they have anal sac disease. If the anal sac has ruptured, you may see blood or pus draining from the rectum.

Symptoms of anal sac disease are:

1. Scooting or dragging the anal area

2. Excessive licking under the tail

3. Soreness or swelling near the tail or anus

4. Bloody or sticky drainage under the tail


How will I know if my dog has anal sac problems?

The first sign is usually “scooting” or dragging the rear along the ground. There may be excessive licking or biting at the anal area or at the base of the tail. Anal sac impaction and infection are painful, so have your pet looked at right away, before the sacs become infected.

How are infected anal sacs treated?

Treatment for impaction involves squeezing and emptying the glands, which your veterinarian or veterinary technician can do.

Oral antibiotics are prescribed if infection is present, and sometimes antibiotic is instilled into the glands themselves.

Treatment may include:

1. Massage to empty the sacs

2. Application of warm, moist heat   (hot packing)

3. Antibiotic medication

4. Instilling medication into the sacs

5. Surgical drainage (lancing)

6. Surgical removal of the sacs


Hot packing reduces swelling and draws out pus. To hot pack an anal gland abscess, fill a bowl with warm water – the same temperature you would bathe or shower in. Dip a washcloth or small towel in the warm water and then hold that to the swollen area. When it cools, dip it in the water again. Continue for 10-15 minutes.

Since infected glands hurt, some pets will require a sedative or an anesthetic to express or treat them, especially cats. Pain medication will be prescribed for abscessed glands and we usually do at least one treatment with our therapy laser to reduce pain and swelling.

Your pet will need to be rechecked in a few days. In severe or recurrent cases, surgery to remove the anal sac(s) may be necessary.

Surgery is usually recommended only if infection is chronic or recurrent. The nerves that control the rectal sphincter muscle are adjacent to the anal sacs, so there is always a risk of nerve damage when surgery is done in this area. There is a 10% chance of fecal incontinence after surgery, either because of the surgery itself or because of the pet licking or scooting and causing damage after surgery.

Is the condition likely to recur?

Many dogs will have recurrent anal sac impaction. In some cases, we have your dog come in every month to express the anal sacs so they don’t have a chance to become impacted. Infection tends to be more sporadic. Our clinic cat, Holly, has had several anal gland abscesses over a two year period, so we check them at least once a month.

If infection or abscessation occurs frequently, especially if the sacs are difficult to express, surgical removal of the sacs may be indicated. Repeated impaction or infection can result in scarring and narrowing of the duct.

Obesity and a poor or low fiber diet are predisposing factors in anal sac disease, so these factors may need to be addressed to keep problems from recurring.

Are there risks attached to surgery? 

The primary concern for surgically removing the anal sacs is permanent damage to the nerves that allow the anus to close. This can result in fecal incontinence and the inability to control bowel movements. While this is rare, occurring less than 10% of the time, we want to minimize the risk of any complication for your pet. We will probably not recommend surgery unless your pet’s anal sac problems have been recurrent and severe.

As with any other surgical procedure, there is also risk from anesthesia. Your pet’s doctor will help you decide which treatment is best for your pet. 

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