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Anal Glands 101

August 22, 2013

Many people know that when dogs and cats scoot their rear on the ground or lick obsessively, it means that the anal glands may need to be checked and emptied. But what exactly are anal glands, and why do they cause so many problems in some pets and no problems at all in other pets?

Dogs and cats have two anal glands (also sometimes called anal sacs). The anal glands are scent-marking glands located under the skin right next to the anus, usually at approximately the “four and eight o’clock” positions. They have short ducts that empty their contents, a watery strong-smelling fluid, directly into the anal opening.

When anal glands are functioning properly, the pressure of the stool against the glands during defecation stimulates them to release some of their fluid to coat the stool. This allows the stool to be used for scent-marking territory, just like animals use urine to mark their territory. Also, if startled or afraid, pets may suddenly empty the entire contents of the anal glands all at once. This may be a defense mechanism to distract rivals or predators.

In our modern pets, many factors can lead to the glands not being stimulated enough to release their contents normally. Many modern pet foods are highly digestible and do not contain the indigestible material such as fur, feathers, or bones that our pets’ wild ancestors’ diets would; this leads to smaller and more compact stools. An episode of diarrhea or chronically soft stools may temporarily not stimulate the anal glands properly. Some individuals have anatomical quirks such as glands that are deeper under the skin, have a smaller duct, or are at an exaggerated angle that make it harder for them to empty naturally. Conditions causing inflammation or swelling in the anal area such as allergies, injuries, or infections may partially obstruct the ducts and prevent the glands from emptying even when they are properly stimulated. Some individuals produce a thicker than normal fluid that cannot be released easily.

Whatever the cause, when the glands do not empty they become overfilled and uncomfortable; this leads to the signs that may be familiar to many pet owners: Most commonly “scooting” or dragging the rear along the ground and obsessive licking of the anal area, but also pain when defecating, reluctance to wag or move the tail, or reluctance to sit down are possible.

Anal glands may be expressed (emptied) manually; it is best to have this done by a professional (a veterinarian or an experienced groomer). In general we do not recommend routine emptying of anal glands in a pet who does not display any symptoms, as this may create inflammation in the anal area that could lead to blockage of the ducts. It is important to have the glands expressed in a pet who is showing symptoms, however, because if the glands cannot empty they may get full enough to rupture and get infected. If this happens repeatedly, scar tissue may develop that perpetuates blockages of the duct.

Any pet may need the anal glands expressed from time to time, and no special additional action is needed for a pet who has only occasional problems. For a pet who has chronic or recurrent problems with the anal glands, some strategies may help stimulate them to empty more normally; for example, diet changes or certain fiber supplements may help some pets. In extreme cases, surgical removal of the anal glands can be performed. If you have questions about specific recommendations for your pet, please call the clinic to speak to one of our veterinarians

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