The anal sacs are located at the 4 o'clock and 8 o'clock positions of the anus, and are embedded in the muscle of the anal sphincter. They are glands that produce a pungent yellowish secretion during defecation.
Anal Sac Impaction
Impaction is more commonly seen in small breed dogs and is the result of large amounts of thick anal sac secretions that cannot be expressed by the dog during defecation. The secretions build up and cause discomfort as the sac becomes distended.
The only symptoms you may notice are scooting or rubbing the anus on the carpet or ground, and excessive licking of the anus or tail base.
This is inflammation of the anal sac, which can be caused by impacted anal sac secretions or bacterial infections of the anal sacs. Anal sacculitis is more painful than anal sac impaction. In addition to scooting and excessive licking, you may notice your pet straining to defecate, being reluctant to sit, or sitting asymmetrically.
Anal Sac Abscess
This is a pus-filled anal sac that results from a bacterial infection. Anal sac abscesses are more painful than anal sac impaction. In addition to scooting, excessive licking, and straining to defecate, you may also notice a red swelling near the anus, or pus dripping from an open wound near the anus if the abscess has already ruptured.
Anal Sac Tumor
Anal sac tumors (apocrine gland adenocarcinomas) are not often painful and do not usually have redness on the overlying skin or any open wounds. They occur mostly in older female dogs, spayed as well as unspayed. They can cause an increase in blood calcium levels, which can cause clinical signs such as increased drinking and urination. They most often spread to the sublumbar lymph nodes, which are located in the abdomen right below the lumbar vertebrae. If the lymph nodes become enlarged due to spread of the cancer, they can obstruct flow of feces by putting pressure on the colon. This may show itself as difficulty defecating or producing ribbon-like stools. Dogs with anal sac tumors can also have symptoms associated with other types of anal sac disease, including scooting, excessive licking, straining to defecate, reluctance to sit, or sitting asymmetrically.
Anal gland removal is indicated in cases of chronic, recurrent anal sac infections and anal gland tumors.