The anal sacs of dogs and cats exist in the rectum, approximately 1/2 to 1 inch from the opening of the anus. They are often misnamed the anal glands, but this is incorrect. The anal sacs are stuctures that collect fluid secreted by the anal glands. As the feces passes through the anal opening upon defecation, the sacs are expressed, and the fluid coats the feces giving it a scent distinct to the animal.
Occasionally in dogs and cats, (more commonly in dogs), the anal sacs do not effectively express, and the fluid collects excessivley in the anal sacs. This causes discomfort and irritation in the anal area. This discomfort leads the animal to lick the area excessively or even exhibit scooting behavior (walking with the front legs while dragging the anus on the floor). If the sacs remain full for too long, an infection can develop, which can be quite severe and painful.
Treatment consists of manually expressing the anal sacs periodically as needed. If the sacs are infected, antibiotics, in addition to manual expression, are required. In cases where the patient suffers from chronic recurring infections, a surgical procedure called an anal sacculectomy can be performed, where the anal sacs are surgically removed. Feeding the patient a high fiber diet will sometimes increase the size of the stool and more effectively express the anal sacs on defecation, decreasing the frequency of necessary manual expressions and lessening the incidence of infections.
