When the anal glands become full or impacted, the dog may experience some discomfort. The glands become VERY itchy and irritated. Actual pain is difficult to assess, but some believe that they can be painful in some cases. When the dog licks, chews or scoots on its bottom, it is attempting to express the glands on its own.

To express anal glands does not require a veterinarian. Many groomers will do this as part of their service, and some pet owners will do it themselves. However, expressing anal glands is not a very pleasant task to perform, and many pet owners will give up after one try. Before trying this on your own, ask your veterinarian for a demonstration.

If anal glands become a common problem, they can be surgically removed. The glands serve no real purpose and, like a human appendix, the dog may do much better without them. Many veterinarians are uncomfortable performing this surgery; however, many others do the procedure with a great deal of success and minimal complications.

How to express the anal glands (sacs)
Anal glands are two sack-like structures located just under the skin near the anus. The size of the anal glands varies between 7 to 15 mm. Normally anal gland secretion is fluid and has the color of light yellow or golden brown. Secretion has a pungent and foul smell. Under normal circumstances a small amount of this secretion is expelled from the gland each time the dog defecates. Also, dogs may occasionally express (to squeeze secretion out) their anal glands when they are frightened. It is not uncommon for anal glands to become impacted. Sometimes the outlet of the anal gland becomes stopped-up and the gland fails to empty properly. This usually leads to discomfort (from the accumulating pressure) and will sometimes lead to inflection.

In order to prevent impaction and other problems in the anal glands it is good to express them regularly, for example when you are bathing your dog. You can express them externally or your vet can express them internally. . With the internal method the gland is squeezed with the index finger inside the anus and thumb outside the anus.  With the external method,  you hold the tail up with one hand and place your thumb and index finger of the other hand underneath the anal glands and press slightly inwards, after which you carefully push the glands with your fingers towards the anus. 

Here is an example of an impacted anal gland..