Cecilia de Cardenas   |   Mar 23, 2009   | Image via iStock.com/mpikula Dogs have anal sacs on either side of the anus that fill with fluid produced by the anal glands. This fluid is a scent marker that’s useful for communicating with other dogs, such as to delineate territory. Anal sac disorders involve impaction of anal sac fluid, inflammation of the sac(s) …