Anal Gland Disease
What are anal glands?
Anal glands (or anal sacs) are small glands underneath the skin on either side of your dog's anus at the 4 O'clock and 8 O'clock positions. They connect to the anus via a small narrow duct. The glands produce a foul-smelling liquid scent which accumulates inside the gland. When the dog passes a motion, this normally puts pressure on the gland and causes some of the secretion to be expressed with the faeces.
What are the anal glands for?
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Dogs often express these glands when frightened. This may have been used by our pet dog's wild ancestors to scare away predators. These glands are highly developed in the skunk.
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As some of the secretion is expressed when the dog defecates, this is probably why dogs smell each other's faeces and bottoms.
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Wild dogs use the glands to scent mark vertical surfaces by rubbing their bottoms on them.
In the modern day domestic dog they are unnecessary and really serve no useful purpose.
What causes anal gland disease?
The secretion is produced whether the gland is emptied or not. When the glands do not express for some reason, the secretion builds up inside the glands. Over time the secretion may solidify, causing a further obstruction to the gland expressing properly which can result in impaction. The pressure that is created in the gland can cause damage to the lining of the gland and this damaged tissue is then susceptible to becoming infected. If an infection is left untreated this can result in an abcess forming which can eventually rupture through the skin, creating an open wound. Abcesses can damage the lining and ducts of the gland, which can result in frequent recurrence of problems.
The reasons for the gland not expressing can include:
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A recent bout of diarrhoea or soft faeces which causes less pressure on the glands when the dog defaecates.
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Overweight dogs are more susceptible as excess fat around the ducts can cause them to block.
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Some dogs are simply born with very small ducts, which do not allow the glands to express easily. This particularly applies to small breeds.
Symptoms of anal gland disease
As the secretion builds up in the gland it causes irritation and eventually pain. The dog will scoot their bottom along the ground to try and relieve this. Scooting can also be caused by tapeworm infestation, skin problems or allergies, but anal gland impaction or infection is by far the most common reason. A drop of foul smelling material may be left where the dog has scooted. Dogs will often lick around their anus or thighs and sometimes bite at their tail. As defecating can become painful, dogs may cry out or yelp while trying to pass a motion. If an infection or abcess is present pus or blood may be seen. Some dogs have glands that drain continuously due to very open ducts, which can lead to frequent drops of anal gland secretion on furniture or around the house.
Treatment of anal gland disease
Diet
Increasing the amount of fiber in the diet can assist with the anal glands emptying by increasing the bulk of the faeces, which then puts greater pressure on the glands when a motion is passed. This can be achieved by adding bran or psillium husk into the food. However, this does not work in a majority of dogs as the duct openings are often just too small to drain properly.
Expressing anal glands
Impaction of the anal glands can be treated by manual expression of the glands by your veterinarian (who can also teach you how to do this if you are interested!). Dogs vary in their production of anal gland secretion, so some effected dogs only need this done every few months, particularly if the glands occasionally express on their own, whereas other dog's glands may fill up in just a week or two.
Anal gland cautery
If the anal glands need expressing constantly, or if infections or abcesses develop, a long-term solution is cautery of the anal glands. This involves each gland being cleaned out and then filled with a caustic solution which burns the lining of the gland, effectively resulting in chemical cautery of the secretory gland tissue. This means that the secretory cells lining the gland are killed and although the gland still remains, the secretion is no longer produced and so impaction no longer occurs. This procedure requires the dog to be under a general anaesthetic as it is, at the very least uncomfortable, if not painful. The dog goes home on pain relieving / anti-inflammatory medication to help with any discomfort which may occur in the first few days after the procedure.
Anal gland cautery is successful in approximately 80-90% of cases. If it does not completely stop production of secretion then it at least reduces it considerably. If the gland has previously been damage by an abcess, this may reduce the efficacy of cautery because the gland lining is often scarred, has folds or pockets, which the caustic solution may not properly distend or contact.
Anal gland removal
If anal galnd cautery is not successful the anal glands can be surgically removed. This procedure is more expensive and more invasive than cautery and can result in complications. The tissue around the anal glands is very delicate. If the anal sphincter muscle is damaged in the operation, faecal incontinence may result. This usually resolves after one to two weeks, but very rarely can be permanent. If part of the gland is not completely removed, the secretion can build up under the skin without any means of drainage, resulting in an abcess, requiring a repeat surgery to remove more tissue. Barring these possible complications, surgical removal does result in complete resolution of anal gland problems.
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