(Impaction, Inflammation, Abscessation)
The anal sacs (sometimes referred to as anal glands) in the dog and cat are paired structures that are located at the 4 and 7 o’clock position next to the anus and act as reservoirs for secretions that are extruded with bowel movements. These secretions are malodorous and are probably part of the scent process and lubrication of stool being passed. These secretions are expelled thru ducts at the edge of the anus during defecation and excitement. Glands that line the anal sacs produce the fluid collected in the anal sacs.
Inflammation of the anal sacs can be the result of chronic impaction from duct obstruction and/or infection. As the inflammation increases this makes the sac more susceptible to infection and worsening of the impaction with possible anal sac abscess and rupture. This condition is painful. Inflammation can also occur without impaction and as the secretion increases, the fluid becomes more pus-like to include some blood. Other anal conditions to include obesity can have some effect on anal sac impaction. Anal sac disease can occur in any breed of dogs and cats and at any age, although it does seem to affect smaller breeds more commonly. Clinically, a patient with anal sacculitis has a very irritated anal area and will lick and scoot and show some degree of discomfort. Straining to have a bowel movement can also be seen. On physical exam, the anal area is inflamed and sometimes swollen and painful. If abscessation and draining tracts have not occurred then no other visible signs will be seen and digital rectal exam is required. This will sometimes require sedation due to discomfort. Rectal exam will reveal enlarged anal sacs that may or may not be able to be easily expressed. The nature of the anal sac secretion is important to assess in terms of infection. Complete impaction is evaluated at this same time and is a real concern for future surgery. Visible abscessation and/or draining tracts (fistulas) warrant a surgical discussion. Routine anal sac digital exam is recommended part of the annual physical or more often if warranted, but excessive digital expression can lead to irritation. The early detection of an anal sac tumor is very important for successful treatment a potentially malignant condition. Radiographic imaging of this area is difficult and is best evaluated with ultrasonography if tumor or tissue invasion is suspected, though many times this is not necessary.
Most anal sac disease problems can be managed medically – antibiotics, manual expression and infusion, anti-inflammatory medication, and diet change to add more bulk. Abscesses need to be lanced and flushed and cleaned daily. Once all of these medical attempts fail, then surgery needs to be considered.
Surgical Management of Anal Sac Disease
Whether it is chronic disease, abscessation, fistulization, infection or simply failed treatment, surgery is the next alternative and is considered curative. Depending on the disease process, unilateral or bilateral anal sacculectomy is performed. In the case of abscessation, medical care should be administered until the tissue is healed and not inflamed. Although an anal sac rupture can heal, it has been our experience that formation of fistulas or reabscessation will occur and surgery is indicated as soon as the tissue is healthy. Bilateral anal sacculectomy is normally the recommendation if the anal sac disease, even if only one sided, is warranted. If the patient is an intact male, it is recommended that castration be performed at the time of surgery to shrink anal tissue. The anal sacs need to be removed in their entirety. Chemical cauterization is never recommended. The surgery consists making a surgical approach lateral to the anus and dissection of the anal sacs intact being careful to protect the nerves to the anus that come in behind the sacs. Anal incontinence is a rare but potential complication and the chances are increased with the severity of disease process surrounding the anal sac. Surgical experience and careful dissection are the keys to success. External sutures are placed and need to be removed 2 weeks following surgery. Postoperatively an E-collar is advised to avoid licking and some cleaning and warm compressing is performed 2 – 3 times per day. Antibiotics and pain relievers are given for 5 – 7 days. If any of the anal sac remains especially after abscessation, a fistula can develop long term.
(Note: See the anal sac carcinoma discussion for anal sac surgery and tumors)