Anal Sac Disease/Infections
Also Known As: Anal sac impaction, anal sacculitis, anal sac abscess
Transmission or Cause: The cause of anal sac infections is unknown. Excessive anal gland fluid production, soft feces or diarrhea, poor muscle tone, and obesity contribute to higher risk of developing anal sac infections.
Affected Animals: Although any dog may be affected, small breeds such as Chihuahuas, dachshunds, and miniature or toy poodles are more commonly examined for anal gland problems. Cats are rarely affected by this condition.
Overview: Anal sacs are the reservoirs for the discharge of anal glands which are located on either side of a dog’s anus. These sacs contain liquid secretions from the anal gland, which, in healthy animals are normally pale yellow-brown to grayish in color. The contents are usually emptied during normal bowel movements or when a dog is nervous or scared. In most animals, these sacs empty easily and regularly. However, some dogs, especially small breed dogs, are not able to empty the sacs properly and become susceptible to anal sac disease. There are three progressive stages of anal sac disease which include: anal sac impaction, anal sacculitis (inflammation), and anal sac abscess.
Description: Impaction of the anal sacs occurs when the anal gland secretions thicken inside the sac and becomes unable to empty during a bowel movement. Anal sacculitis, or inflammation of the anal sac, is an infection usually resulting from impaction but may also be caused by bacterial growth within the anal sac. During the sacculitis stage, the impacted fluid may become thinner and fill with pus. Abscess occurs when the inflammation of the anal sac has reached an extreme stage. At this point, a red-brown substance will be seen coming from the sac. The sac will usually be enlarged, warm, red, and painful. Usually, the abscessed sac will rupture, leaving a hole near the side of the rectum that oozes a foul-smelling liquid. The tissue surrounding the abscess will swell, causing more inflammation and pain.
Clinical Signs: Symptoms of anal sac disease include scooting across the floor, licking the area around the anus, straining to defecate, biting at or chasing the tail, discharge, swelling, and/or pain around the area. A dog with anal sac disease may scoot their rear end on the ground in an attempt to relieve the sensation of pressure and irritation around its rectum. When an abscess ruptures, pus discharge may be seen draining from the lesion. The area surrounding the abscess may appear red, swollen, and painful.
Diagnosis: Diagnosis of anal sac disease is made clinically with a rectal examination. Infected anal sacs are often very painful and some dogs may need sedation before a thorough examination can be done. Normal anal sac fluid varies in color but brown, yellowish-green, or red tinged secretions are typical of animals with anal sac disease.
Prognosis: Most often antibiotics will resolve the anal sac infection. In many cases, expressing the anal sacs must be performed on a regular basis to prevent recurrence.
Treatment: When the anal sac disease is at the impaction stage, the most common treatment is an outpatient procedure called expression in which the veterinarian applies pressure to the anal glands until the thickened secretions are expelled from the sacs. For the anal sacculitis stage of the disease, the same expression procedure is performed and afterwards, an antibiotic-steroid combination ointment is applied directly to the anal sac. In addition, the examining veterinarian may prescribe oral antibiotics to help fight infection. When anal sacs have abscessed, a surgical procedure is sometimes necessary. After sedating the dog or placing it under general anesthesia, the veterinarian will surgically open the infected anal sac to clean out the infected material and drain the remaining liquid. An oral antibiotic will usually be prescribed post-surgery. If infection continues after the surgery, surgical removal of the anal sac may be required.
Prevention: Expression of the anal sacs every few weeks or months often will help prevent anal gland fluid from accumulating and becoming thickened. High fiber diets are suggested to help prevent anal sac disease in some dogs, especially those that are obese.