Structure and Function of Anal Glands in Dogs

Below is information about the structure and function of the canine anal gland. We will tell you about the general structure of the anal gland, how anal glands work in dogs, common diseases that affect the anal glands and common diagnostic tests performed in dogs to evaluate anal glands.

What Are the Anal Glands?

A dog’s anal glands (also called anal sacs) are two glands that secrete a pungent fluid that travels through tiny ducts that open into the dog’s anus. Typically, this fluid is released during defecation.

Where Are the Anal Glands Located in Dogs?

The anal glands are located on either side of the anus, just under the skin, at the 4 o’clock and 8 o’clock positions. The glands are embedded in the muscle of the anal sphincter and are not readily visible.

What Is the General Structure of the Anal Glands?

The anal glands are small oval shaped glands. The tissue within the glands produces a fluid that is collected in a multitude of tiny ducts. As feces pass through the anus, the glands are squeezed and the duct releases the fluid through small pores.

What Is the Function of the Canine Anal Glands?

The only known function of the anal glands is to produce small amounts of anal gland secretions, ranging in color from yellow brown to gray. It is theorized that these secretions are used as a way to mark territory and identify other dogs. The secretions from these glands are very pungent and may also be expressed when the animal is frightened or alarmed.

What Are Common Diseases of the Anal Glands in Dogs?

Many animals do not develop problems with these glands and many people are unaware of their presence. In a few animals, anal gland impactions, infections, abscesses, rupture and even tumors can occur. Diseases of the anal glands vary in severity. Common symptoms of anal gland disease include “scooting” – dragging the rear end across the floor, a foul odor, pain, and/or licking or attempts to lick/bite at the rectal area.

Anal gland impactions are the most common disorder associated with the anal glands. For an unknown reason, the fluid produced in the glands becomes too thick to be expressed naturally through the pores of the glands. The fluid continues to be produced, resulting in an enlargement of the gland and irritation.

Anal gland infections are typically bacterial infections, causing irritation and inflammation. Anal gland abscesses are a progression of anal gland infections. The infection worsens and causes a significant accumulation of pus within the anal gland. Anal gland rupture is the final stage of an anal gland infection. The abscess will continue to enlarge until it eventually ruptures and pus drains.

Anal gland tumors are most often malignant and are classified as adenocarinomas. Sometimes, anal gland tumors can result in elevated blood calcium levels, which can cause significant organ damage, including kidney failure.

What Types of Diagnostic Tests Are Used to Evaluate the Anal Glands?

Physical examination and rectal palpation are the primary methods of evaluating the anal glands. Rectal palpation is performed by inserting a gloved finger into the rectum to feel the gland. Radiographs (x-ray) and blood work are not typically used to evaluate the anal glands but can sometimes suggest an anal gland abnormality, which prompts further exam of these glands. Abnormal glands that are suggestive of a tumor may be diagnosed with a biopsy.