By T. J. Dunn, Jr., DVM

Few topics raise dog owners’ eyebrows (and lower dogs’ tails) faster than the subject of anal glands. These two small structures are renowned for the foul-smelling material they produce, but what is their purpose and what should pet parents do when something goes wrong with them?

What Are Anal Glands?

Anal glands, or anal sacs as they are sometimes called, are small paired pouches located between the internal and external anal sphincter muscles, one on each side of the anus at roughly the 4 and 8 o’clock position. They empty through short and narrow ducts just inside the anus. Each sac is lined with abundant, modified sebaceous (oil) and apocrine (sweat) glands. The secreted substance is normally an oily, brownish fluid that packs a strong odor.

Liquid held inside the sac is usually expelled when a dog defecates, but if this does not occur on a regular basis, the material inside thickens, which makes it harder to pass. If this situation persists, the gland may become impacted, inflamed, and infected. The gland can even abscess and rupture through to the skin surface.

What Do Anal Glands Do?

There are a number of theories why dogs, cats, and other mammals have anal glands and what possible use they may have. One states that anal sac contents, when excreted with the passing stool or by anal sphincter muscle contraction, act as a powerful territorial scent marker. Another theory states that the anal sac material lubricates hard stool, which makes passage easier.

Causes of Anal Gland Problems

One study indicated that anal gland disorders affect about 12 percent of dogs. Problems are seen less frequently in cats, but they are still possible. It is often difficult to determine why some pets suffer painful anal sac disorders while others do not. Obese animals do seem to have more trouble with their anal glands than do slimmer individuals, probably because extra body fat in the anal region lessens the pressure that passing feces applies to the glands. Similarly, pets who have chronically soft stools tend to be at higher risk of anal gland problems. Some individuals may be born with very narrow ducts that drain the glands, thereby obstructing the flow of anal sac material. Acquired damage to the duct can occur with perianal infections, trauma, allergies, or inflammation. Other potential causes include anal sphincter muscle dysfunction, distended anal glands, and overproduction of anal gland material.

Age/Breed Considerations

Relatively uncommon in cats and large breed dogs, anal gland infections and impactions are more often diagnosed in small breeds such as Toy and Miniature Poodles, Chihuahuas, and Lhasa Apsos. Cocker Spaniels, Basset Hounds, and Beagles also rank high on the list of breeds affected by anal gland difficulties. Dogs of any age and either sex can be affected.

The Role of Diet

While a change in diet alone won’t resolve a significant anal gland problem once it has developed, feeding a diet rich in fiber may help prevent future recurrences. The pressure of the firm, bulky stool against the colon wall near the anus can help to express the anal gland contents when a pet defecates.

Groomers

A difference of opinion exists regarding whether or not healthy anal glands should be routinely expressed by hand. Many veterinarians suggest that this should not be done in a normal dog with no history of problems. Many groomers make it a matter of routine, however, to express the anal glands of the dogs under their care.

Certified Master Groomer Sherri Glass, for example, has been grooming dogs since 1993 and has taught pet grooming at Cornerstone Dog Grooming Academy in Clyde, Ohio. She relates, "[we] teach students to empty anal glands on all small dogs, about 20 pounds or less in size. We also do any size dog at the owner's request." But she adds, "If dog owners would meet their dog's nutritional needs with high-quality food, keep them at proper weight, and provide plenty of good exercise, most dogs would not have to have the anal sacs expressed."

Jeffrey Reynolds, director of the National Dog Groomers Association of America, adds that groomers won’t actually treat diseased glands. "When there is evidence that the sacs are impacted, then they are not expressed and the owner is advised to bring the dog to the vet."

If you are concerned that frequent anal gland expressions may be causing your dog more troubles than they are solving, you can always request that your groomer skip this step.

How to Recognize a Problem

Most pets who are having problems with their anal glands will scoot their bottom along the floor, frequently turn to lick or bite at the anal region, or display discomfort when passing stool. Any pet with persistent symptoms like these should be evaluated by a veterinarian. Left untreated, anal sac impactions, infections, and abscesses can become serious problems for your dog, so be proactive about an evaluation if your dog displays any discomfort in the anal region.

Treating and Managing Anal Gland Problems in Pets

Veterinarians check a pet’s anal glands with a digital rectal exam—inserting a lubricated, gloved finger through the pet’s anus and feeling the surrounding structures. The doctor will also express each gland to evaluate the material and how easily it can pass through the ducts. This is usually the only treatment necessary if a pet’s anal glands are mildly impacted.

If your pet is diagnosed with an infection, your veterinarian will prescribe antibiotics and perhaps other treatments like warm compresses and pain relievers. An abscessed anal gland may also need surgery to provide drainage and to remove damaged and infected tissues. Regularly scheduled anal gland expressions can help prevent impaction and infection in dogs who suffer from recurrent anal gland problems. This procedure can be performed by your veterinarian or groomer, or you can ask to learn how to do it yourself at home.

While impaction and infection are the most common anal gland problems in pets, other conditions, including cancer, can affect the perianal region of pets. If you suspect that your dog or cat is suffering from an anal gland disorder, make an appointment with your veterinarian.

perianal Something around the anus

sphincter A ring-shaped muscle that is used to close and open an opening

ducts A passage in the body with walls

anus The end of the gastrointestinal tract; the opening at the end of the tract.

anal glands Tissue located inside the anal sac that aids in the marking of territory in animals, for defense, or for sexual behavior.