Anal Sac Disease in Dogs
What are the anal sacs?
The anal sacs are two small pouches located on either side of the anus at approximately the four o'clock and eight o'clock positions. The walls of the sac are lined with a large number of sebaceous (sweat) glands that produce a foul smelling fluid. The fluid is stored in the anal sacs and is released through a small duct or canal that opens just inside the anus. The anal sacs are commonly called 'anal glands'. The sacs are present in both male and female dogs.
What is their function?
The anal sac secretion contains chemicals that act as territorial markers or 'dog calling cards'. The secretions are similar to those produced by a skunk, which are used to repel enemies and alert other animals to their presence. Anal sac fluid is usually squeezed out by muscular contractions whenever the dog passes a bowel movement, providing a distinctive odor (or individual 'scent signature') to the feces. This is why dogs are so interested in smelling one another's feces.
Why are the anal sacs causing a problem in my dog?
Anal sac disease is very common in dogs. The sacs frequently become impacted (plugged) usually due to inflammation of the ducts. The secretion within the impacted sacs will thicken and the sacs will become swollen and distended. It is then painful for your dog to pass feces. The secreted material within the anal sacs is an ideal medium for bacterial growth, allowing abscesses to form. Bacteria that are normally present in the feces can readily travel up the ducts and enter the sacs. In normal situations, the bacteria are flushed out when the secretions are expelled during a bowel movement. However, if the sacs are impacted, the fluid does not empty normally and they become infected. The fluid then becomes bloody and eventually the sacs become filled with pus, forming an anal sac abscess.
"Anal sac disease is very common in dogs."
The abscess will appear as a painful, red, hot swelling on one or both sides of the anus. If the abscess bursts, it will release a quantity of greenish yellow or bloody pus. If left untreated, the infection can quickly spread and cause severe damage to the anus and rectum.
Another cause of recurrent anal sac disease is change in stool consistency. This can occur in dogs with gastrointestinal diseases such as food allergies and inflammatory bowel disease.
How will I know if my dog has anal sac problems?
The first sign is often scooting or dragging the rear along the ground. There may be excessive licking or biting, often at the base of the tail rather than the anal area. Anal sac disease is very painful. Even normally gentle dogs may snap or growl if you touch the tail or anus when they have anal sac disease. If the anal sac ruptures, you may see blood or pus draining from the rectum.
How is anal sac disease treated?
Treatment for impaction involves expressing or emptying the sacs. If the impaction is severe or if there is an infection, it may be necessary to flush out the affected sac to remove the solidified material. Since these conditions are painful, some pets require a sedative or an anesthetic for this treatment.
Antibiotics (e.g., clindamycin, brand name Antirobe®, Cleocin®) are often prescribed orally and sometimes may need to be instilled into the sacs. Most dogs will require pain relief medications (e.g., meloxicam, brand name Metacam®) for several days until the swelling and inflammation have subsided. In advanced or severe cases, surgery may be necessary.
"If you are concerned that your pet may have an anal sac problem, call your veterinarian at once."
Problems with the anal sacs are common in all dogs, regardless of size or breed. If you are concerned that your pet may have an anal sac problem, call your veterinarian at once.
Is the condition likely to recur?
Some dogs will have recurrent anal sac impactions or abscesses.
"Overweight dogs tend to have chronic anal sac problems because their anal sacs do not empty well."
Overweight dogs tend to have chronic anal sac problems because their anal sacs do not empty well. Each impaction may cause further scarring and narrowing of the ducts, leading to recurrences that are even more frequent. If this condition recurs frequently, surgical removal of the sacs is indicated.
If the cause of anal sac disease is change in stool consistency, prevention involves treating the underlying cause and may require changing the dog to a higher fiber diet.
Are anal sacs necessary for my dog? Will removal have any adverse effects?
Anal sacs produce the pungent smelling secretion that allows the dog to mark his or her territory. For our domesticated dogs, this is an unnecessary behavior and removal will not adversely affect your pet.
Are there any risks associated with surgical removal of the anal sacs?
Removal of the anal sacs is a delicate and specialized surgery. Some veterinarians perform this procedure routinely; however, in severe cases, your veterinarian may recommend referral to a board-certified veterinary surgeon. Some dogs will experience loose stools or lack of bowel control for one to three weeks following surgery. This occurs because the nerves controlling the anal sphincters (muscles that close the rectum) run through the soft tissues near the anal sacs. If the infection is deep and extensive it can be impossible to avoid damaging the nerves during the surgery. This damage resolves without further treatment in the majority of pets. In rare cases, the nerve damage is permanent can result in fecal incontinence or the inability to control bowel movements, with constant leakage of feces from your dog's anus.
"Removal of the anal sacs is a delicate and specialized surgery."
As with any surgery, general anesthesia is required which always carries some degree of risk. Advances in anesthesia drugs and monitoring continue to decrease these risks. For dogs suffering from chronic or recurrent anal sac infection or impaction, surgical removal is the best option to relieve the pet's pain.
My dog is very nervous and sometimes seems to express his own glands. Is this normal?
It is common for dogs to release the contents of their anal sacs, particularly if frightened. Some dogs even appear to lack control of the anus or anal sac ducts so that small quantities of fluid will drain out when they are resting, leaving an unpleasant lingering odor in the home. If your dog has this problem, you may elect to remove the anal sacs.
What other problems can develop with the anal sacs?
Older dogs can develop cancer of the glands within the anal sacs called adenocarinoma. Therefore, it is very important to have your dog examined by a veterinary as soon as any of the above clinical signs are seen.
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