The anal glands are small glands that sit on each side of the rectum and are filled with a thick smelly discharge. They are normally expressed naturally as pets have bowel movements. A small amount of the anal gland discharge is released with the bowel movement allowing pets to "mark territory".
These glands can become clogged in some pets causing problems. When they become clogged, pets may lick their rectums or "scoot" their bottoms on the floor in an effort to relieve the discomfort.
Many groomers routinely express the anal glands when pets are bathed and groomed. Some pet's owners also attempt to do this procedure at home.
There are two basic ways to express the anal glands – exteriorly and interiorly. The interior method is generally what your veterinarian does at which time they put on a glove, insert a finger into the dogs rectum at which time they can feel the gland between the anal wall and their finger. This allows them to fully feel and express the gland. The exterior method allows you to express the glands from the outside. To do this, you basically pinch the rectum closed trying to squeeze the glands as you do it.
For more information on anal glands problems, please read Anal Gland Removal in Dogs
and Structure and Function of the Anal Glands