Anal Sac Diseases


The anal sacs (also called anal glands) are two small pockets located just inside the anus, on the left and right sides of the anal canal in dogs and cats. Normally they produce a smelly, clear to light yellow liquid secretion, which is expressed from two small pores when the animal defecates. They can also discharge this odorous secretion spontaneously, or when the dog or cat is startled, injured, or excited. Several different types of problems can arise from the anal sacs. These include inflammation, infection, and even tumor formation. Dogs, especially small breeds, are more commonly affected than cats. The most common anal sac problems are:

  • Impaction—failure of the anal sacs to discharge, resulting in inspissation (drying out and hardening) of the contents, which then accumulate, causing discomfort as for hemorrhoids in people.
  • Abscessation—bacterial infection of the sacs, usually following an impaction. Inflammation and pain in the area will be present. The abscess can often burst through the sac, draining pus and blood onto the skin and haircoat around the anus.

The diagnosis of anal sac disease is made based on history (what you have observed as your pet’s symptoms) and the physical exam performed by the veterinarian. In terms of symptoms, dogs with anal sac impaction or abscessation are often reported to “scoot,” meaning they drag their rear end across a floor or carpet by pulling themselves along with their front legs while sitting upright. They also may attempt to lick the area frequently or seem “bothered” by discomfort. You might notice a change in their stool habits. This can be either a variation in the shape of the feces (thin, like a ribbon) or pain when attempting to defecate. On physical examination, your veterinarian will perform a digital rectal palpation to check the anal sacs. He or she will attempt to express (empty) the anal sacs manually by applying gentle but firm pressure. If this is too difficult or too painful for the dog, sedation may be necessary in order to expel the contents and be sure impaction is not present. Various degrees of inflammation (redness, heat, swelling, pain) of the region around the anus may be apparent when a dog or cat has anal sac disease, and the material in the sacs may be dark and flocculent (with chunks) or firm like clay. There may be pus and/or blood present in the sacs, or draining through the skin beside the anus from an abscess that has already burst.


Luckily, anal sac impaction or abscessation generally is not a serious illness. It can, however, be a chronic problem and can recur frequently, causing discomfort. Many dogs are affected for no apparent reason. There are no preventative measures to guarantee that the problem never returns. The most important thing is to monitor your pet’s behavior and defecation habits and seek veterinary attention if constipation or pain becomes apparent.


In the case of impaction, your veterinarian can often help by expressing the anal sac material. During a rectal palpation, pressure is applied the sac to empty it. If this is painful or the material is too hard, sedation of the dog or cat is recommended so the emptying can be done without discomfort. Occasionally, a small tube (catheter) is placed into the sac through the pore, and the sac is irrigated with saline to flush it. This can help soften very hard material if present. Depending on the degree of inflammation, your veterinarian may prescribe antibiotics or antiinflammatories. These medications should be given as directed.

Often, the first sign of an anal sac abscess is when you see pus and/or blood draining from the anal area beneath the tail after the abscess has burst through the skin. Owners of affected dogs or cats report seeing blood staining around their pet’s anus. If the abscess has not yet burst, your veterinarian will often lance the infected anal sac while your pet is under sedation and flush the area with saline. It is important that the lanced abscess remain open for as long as possible to fully drain the infected material. Warm compresses can help, and your veterinarian may recommend that you apply warm-packs to the area two or more times a day. A good way to do this is to take a moist facecloth and place it in the microwave for 10-20 seconds, then remove it and carefully (handle carefully, to not burn yourself) check it to make sure it is not too hot. Then this lukewarm facecloth can be put in a Ziploc-type bag and applied to the affected area. Antibiotics and antiinflammatory medications (in the form of pills to be given by mouth) will likely be prescribed.

If the problem recurs, the anal sacs may have to be expressed repeatedly. Some dogs require this procedure every 1 to 2 weeks after having an episode of impaction, gradually decreasing the frequency to whenever necessary. Your veterinarian may be willing to show you how to do this at home. It has been reported that a change in the diet, such as increasing the fiber content, can be beneficial. By altering the stool, the anal sacs may express themselves without intervention. Your veterinarian may recommend a different dog food or additives such as bran or Metamucil to your pet’s regular food.

In refractory (nonresponsive) cases where symptoms persist despite treatment, it may be advised to have the anal sacs removed altogether (anal sacculectomy). This is a surgical procedure in which one or both sacs are removed under general anesthesia. It is not a difficult operation, but there is always a small risk of complications such as infection or compromise of the anal sphincter, resulting in fecal incontinence. It is a delicate but short procedure, and the patient usually goes home the next day with some home care such as warm compresses and pain medication (antiinflammatories) and antibiotics.


  • Follow your veterinarian’s instructions regarding medication and recheck appointments.
  • Become familiar with your pet’s defecation habits. Be aware of any changes in stool shape (thin and pencil-like) or behavior (pain or straining to defecate, scooting, looking anxiously at hind end).
  • Have your pet examined if you notice repeated “scooting” (more than once every few months), recurrent licking at the anal area, or any sign of discomfort when defecating.
  • Understand that anal sac disorders can be difficult to treat, and that a second opinion from a veterinary internal medicine specialist may be helpful. You can discuss this with your veterinarian and a list of these specialists is available at,, or for North America; or at or for Europe.


  • Don’t wait until the problem recurs to have a recheck appointment if your pet has had an anal sac problem requiring treatment. Since anal sac problems often return, it is best to have your veterinarian continue to monitor your pet until the anal sacs are functioning normally and not causing symptoms.


  • If you are unable to give any medication prescribed as directed.
  • If you notice signs of severe pain or straining to defecate, or if your pet fails to produce any stool in 24 hours.


  • Scooting, licking at the hind end, pain on defecation, swelling or drainage around the anus.


  • Your veterinarian will offer recheck appointments based on the severity of the case. As mentioned, many dogs require routine expression of their anal sacs. The frequency will depend on the patient.


  • Inflammation of the anal sacs is called anal sacculitis and can include impaction or infection/abscessation. Other more serious conditions can result in similar symptoms and should not be mistaken for anal sac impaction or abscessation:
    • Perianal fistulas—a severe, chronic disease of the area around the anus. Multiple draining tracts are present, which are deep fissures in the skin surrounding the anus. The anal sacs themselves are not involved. German shepherds are most commonly affected.
    • Anal sac tumors (adenocarcinomas)—malignant tumor of the anal sac, occurring more commonly in older dogs.

These tumors can often spread to regional lymph nodes, which enlarge and obstruct the path of feces. If this type of cancer is suspected, your veterinarian will likely recommend blood work and x-rays to confirm and check for spread of the disease. Removal of the anal sacs and possibly the lymph nodes may be offered, followed by chemotherapy. Consultation with a veterinary oncologist (see www.acvim.orgor for listings of these specialists) is an excellent option for obtaining a second opinion and the most comprehensive information on treatment options and outcomes. Anal sac tumors are much less common than anal sac impaction or abscesses.

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Chappelle Veterinary Clinic is a full service Veterinary Clinic which offers a wide range of veterinary care for cats and dogs, including routine exams, vaccinations, preventative care, diagnostics, surgery, spay and neuter, wellness services, dental cleaning, emergency and more.

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