Anal Sac Disease in Cats

What are the anal sacs?

The anal sacs are two small pouches located on either side of the anus at approximately the four o'clock and eight o'clock positions. The walls of the sacs are lined with many glands that produce a foul-smelling fluid. This fluid is stored in the anal sacs and then released through a small duct that opens just inside the anus. The anal sacs are commonly referred to as anal glands. The sacs are present in both male and female cats.

What is the function of anal sacs?

The fluid that anal sacs secrete contains chemicals that act as territorial markers, or cat “calling cards”. The secretions are similar to those produced by a skunk, which are used to repel enemies and alert other animals to their presence. Anal sac fluid is usually squeezed out by muscular contractions whenever a cat passes a bowel movement, providing a distinctive odor (or unique “scent signature”) to the feces.

What diseases affect the anal sacs?

The anal sacs and ducts can become inflamed or infected for a variety of reasons. If the anal sac ducts become swollen, the fluid cannot be emptied properly from the sacs during defecation. In this situation, the sacs may become impacted (plugged) and the fluid becomes thicker and darker in color.

The secreted material in the anal sacs is an ideal medium for bacterial growth, allowing infections to form. Bacteria that are normally present in the feces can readily travel up the ducts and enter the sacs. In normal situations, the bacteria are flushed out when the secretions are expelled during a bowel movement. However, if the sacs are impacted, the fluid does not empty normally, and they become infected. The fluid then becomes bloody and, eventually, the sacs become filled with pus, forming an anal sac abscess.

The abscess will appear as a hot, painful swelling on one or both sides of the anus. If the abscess bursts, it will release greenish-yellow or bloody pus through an opening in the skin beside the anus. If left untreated, the infection can quickly spread and cause severe damage to the anal area. Occasionally, infections occur without impaction, and the anal sac contents can drain through the duct and be seen coming out of the anus.

What are the clinical signs of anal sac disease?

Signs of anal sac disease depend on the nature and severity of the problem. The first signs are scooting or dragging the anal area along the ground and licking or biting at the rectum or the tail. Affected cats may also show hair loss around the base of the tail or on the belly, due to excessive grooming. Your cat may also be reluctant to defecate.

Anal sac disease is very painful, and even a normally gentle cat may scratch or bite if you attempt to look at the affected area. If one or both anal sacs become abscessed, the area beside the rectum may be swollen. If the abscess ruptures, you will see a bloody or sticky discharge draining beside or beneath the rectum.

How is anal sac disease treated?

The treatment for impaction is to express the sacs and flush out any solidified material. Infusing the affected sac with anti-inflammatory and antibiotic medication may also be required. This treatment can be painful, so it may require sedation.

The treatment for infection is to express the sacs and administer oral antibiotics to kill the bacteria. Most cats respond well to pain-relief medications and antibiotics. Your veterinarian may also recommend using warm compresses for additional pain relief. If the abscess has already ruptured, you may need to gently clean the area regularly until it heals. If your cat is licking the area, they should wear a cone collar.

Your veterinarian will let you know when your cat should be reassessed. At this reassessment, they will likely express the anal glands again and may provide a repeat infusion of anti-inflammatory and antibiotic medication.

If the anal sacs are abscessed but have not ruptured, surgical treatment may be necessary to lance the abscess.

Is the condition likely to recur?

It is not very common for cats to have recurrent anal sac disease, but it can happen in cats with obesity, chronic diarrhea, chronic constipation, inflammatory bowel disease, allergies (including food allergies), and abnormal anatomy or neurologic function.

If your cat experiences recurrent anal sac disease, have them assessed and treated for any underlying conditions to reduce recurrence. Cats with recurring anal gland issues may benefit from having their glands expressed (emptied) on a routine basis by veterinary professionals.

If your cat has several episodes of anal sac disease and recommended treatments do not relieve the problem, the anal sacs can be removed surgically.

Are anal sacs necessary for my cat?

Anal sacs produce a pungent smelling secretion that allows cats to mark their territory and repel predators. For domesticated cats, this function is unnecessary and removal will not adversely affect your pet.

Are there any risks associated with surgical removal of the anal sacs?

Removal of the anal sacs is a delicate and specialized surgery. Some veterinarians perform this procedure routinely; however, in certain cases, your veterinarian may recommend referral to a board-certified veterinary surgeon.

Some cats will experience a lack of bowel control after the surgery. They may drop fecal balls while walking or experience fecal incontinence when they sleep or lie down. This occurs because the nerves that control the anal sphincters (muscles that close the rectum) run through the soft tissues near the anal sacs. If the infection is deep and extensive, it may be impossible to avoid damaging the nerves during the surgery. In most cases, this is a temporary problem that will resolve within a few days to a few weeks of surgery. In rare cases, nerve damage is permanent and can result in chronic fecal incontinence.

If your cat is suffering from chronic or recurrent anal sac infection or impaction, surgical removal may be the best option to relieve the pain. Your veterinarian will thoroughly discuss the risks and benefits of surgery with you.

What other problems can develop with the anal sacs?

Older cats can develop cancer of the glands in the anal sacs called adenocarcinoma. Symptoms are similar to an infection and include swelling beside the anus, dragging the back end, and excessive licking. Therefore, it is important to have your cat examined by a veterinarian as soon as you see any clinical signs.