Skip to main content

Anal Sac Disease

  • All dogs and cats have two anal glands located beside their anus. These glands are often called anal sacs.
  • Most animals express their anal sacs when they defecate.
  • Some animals experience a build up of fluid in their anal sacs, which can lead to discomfort and itching.
  • Anal sacs can become infected or abscessed (pus-filled and inflamed), which can require medical treatment or surgery.

What Are Anal Sacs?

Anal sacs are a set of glands that are just under the skin near your pet’s anus. The two glands arelocated at the 4:00 and 8:00 o’clock positions from the anus. The anal sacs fill with a foul-smelling fluid that is normally expressed through a tiny duct when animals defecate. Animals may use their anal glands to mark territory or repell aggressors, although a nervous dog or cat may accidentally express these glands when frightened.

If an animal cannot naturally empty ananal sac during defecation, the sac fills with fluid, becoming increasingly swollen. This is called an impacted anal sac, which can become painful and irritating to the animal. Some pets drag or “scoot” on their rear end to try to relieve pain and empty the glands. Pets may also lick the area to relieve discomfort.

If impacted anal sacs are not emptied, they continue to swell with fluid, leading to inflammation. Eventually, the area becomes infected, and an abscess (pus-filled inflammation) can form. In some cases, the abscess can rupture through the skin. This condition can be extremely painful to the pet and requires immediate medical treatment. In some cases, particularly if the problem happens several times to the same animal, surgical treatment may be recommended.

Anal sacs can also develop tumors that can be malignant (cancerous), which means that the cancer can spread to other areas of the body.

Signs of Disease

  • Scooting on the rear end
  • Licking, chewing, or “chasing” the anal area
  • A foul odor around the anal area
  • Swelling or bleeding around the anus
  • Straining to defecate
  • Pain during defecation


Your veterinarian can diagnose many anal gland issues by examining the area and feeling the glands. For pets that are in a lot of pain, sedation may be recommended so that a thorough examination can be performed. During the examination, your veterinarian will look for redness, signs of pain, swelling, or the presence of pus, which indicates infection. If a thickening, lump,or growth is present, your veterinarian may recommend a biopsy (collecting and testing a small sample of tissue) to help determine whether the tissue is cancerous.


Expressing the anal sacs describes the manual removal of fluid that has accumulated in the anal glands. This can be performed at the veterinary hospitalor even at home by a pet owner after careful instruction. Some groomers routinely express anal sacs before bathing pets. If a pet is having any type of problem with the anal sacs, it is best to let a veterinarian examine the pet and express the sacs if necessary.

Examination gloves should be worn when attempting to express anal sacs. The technique involves placing a paper towel over the anal area and gently squeezing with the thumb and index finger to remove the fluid. Care must be taken to avoid rupturing the sac or otherwise injuring the pet’s rectum or anus. If you are unsure of whether or how to express your pet’s anal sacs, ask your veterinarian to perform this procedure on your pet.

If the anal glands are infected or abscessed, your veterinarian will empty the glands to remove the fluid. Your veterinarian may also flush out the sacs with antiseptic solution and insert ointment to relieve pain and inflammation. Antibiotics, pain medication, and medication to relieve inflammation may also be prescribed.

Surgical removal of the anal glands may be recommended for animals that have had repeated anal gland issues or infections. Your veterinarian will talk to you about the benefits and risks of this procedure and whether it may be a good option for your pet.


The best way to prevent anal sac issues is to frequently express the anal sacs if they are not emptying on their own. This helps prevent the sacs from filling with fluid. Some experts recommend adding fiber to the pet's diet, which helps naturally express fluid from the anal sacs.