Anal Sac Disorders

Pet Tales
by Barry B. Burtis D.V.M.

Anal Sac Disorders

When I am about to go into the examination room to see a client with their pet, I usually check first, the tracking sheet that accompanies the patient's chart. In a small corner of the sheet, the receptionist will have written the reason that the client has given, for the pet's visit. It may say something like, "vaccines"," check ears", or "limping". Seeing what is written will begin my thinking process as to what I will be dealing with in the consultation.
If, in that space, I see any of the following, "chasing or biting tail", "rubbing bottom on floor", "scooting", "noticing bad odour at rear", or "sore behind", I immediately know one part of the pet's anatomy that will need investigation.  In my experience, anal sac disorders will have a high likelihood of being involved with such complaints.

Anal sacs are two small glands that are located in the subcutaneous tissue beneath the skin, on either side of the anus. They empty via a small duct found just inside the anal sphincter. All dogs and cats have them. They produce a glandular secretion that usually has quite an offensive odour. The sources of the very awful smelling spray that skunks can emit are the slightly modified anal sacs that they possess. In normal circumstances occasionally when a cat or dog passes stool, the anal sacs will empty of their contents. They do not serve any worthwhile purpose for our pets today. Sometimes they can be a cause of problems. It is estimated anal sac disease affects about 12 per cent of the canine population. It is much less frequently diagnosed as a problem for cats.

There are three main problems that anal sacs may cause for dogs - impaction, sacculitis and abscesses. Tumours of the anal sac are almost always malignant but fortunately are quite rare in dogs and have not been reported in cats. Impaction happens if for some reason normal emptying of the sac does not occur. The anal sacs become swollen and become a source of discomfort. Owners will notice their pet showing one or more of the symptoms mentioned earlier. Examination of the area around the anus may reveal a slight bulge of the skin overlying one or both of the anal sacs. Rectal examination by a veterinarian will usually confirm the presence of thick, pasty, gray-brown material when the sacs are expressed. Occasionally, when the contents have become very thickened or condensed, the sacs will need to be irrigated with a warm saline solution or mineral oil to help evacuate the contents. After emptying the sacs, they are often flushed with an antibiotic/anti-inflammatory preparation.

If impaction alone has been the cause of the pet's problem, emptying the sacs should bring about very prompt relief. Some pets, for no known reason, may require this assistance from a veterinarian on a regular basis. However, in my opinion, for most pets their anal sacs should only be examined and expressed if they are showing signs of trouble.

Sacculitis occurs when bacteria invade the anal sac and though the presenting signs shown by the patient will be similar to those having impaction only, the veterinarian will notice differences on examination.  Palpation of the affected area is more painful. The material expressed from the infected sac is greenish yellow or cream-coloured and sometimes mixed with flecks of blood. The patient may have a fever. In addition to emptying and flushing the infected sacs with an antibiotic solution, antibiotics given by mouth will be prescribed for 10-14 days. Follow-up visits will be necessary to assure healing has been achieved.

The presence of pus and/or blood draining from an area just to side and below the anus in a dog or cat may be the first sign noticed in a pet that has an anal sac abscess.  If an abscess develops in an anal sac, the patient is put under sedation or general anesthesia to allow proper treatment. The abscess will need to be lanced and drained if it has not yet ruptured spontaneously. Appropriate local cleaning and care of the affected area will be necessary. Antibiotics should be given until healing is complete.

If any of these anal sac disorders recur with any frequency, your veterinarian will likely recommend sacculectomy - the surgical removal of both anal sacs. As mentioned they have no purpose and it is the only way of being sure they will never bother the pet in the future.