Anal Sac Disease in Dogs

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Overview of Canine Anal Sac Disease

The anal sacs are glands located near the anus (rectum) that produce secretions that are normally expressed during defecation in dogs. The secretions from these glands are normally pungent (in fact, very smelly) and straw-colored with brown flecks. Anal sac contents may also be expressed in times of fright (producing a terrible odor in the area).

Dogs are more commonly affected with anal sac disease than cats, and small breed dogs are more commonly affected with anal sac impaction than large breed dogs. Older female dogs are more commonly affected with anal sac tumors.

Types of Anal Sac Disease in Dogs 

Types of disease include: 

  • Impaction, which can lead to inflammation or infection of the anal sacs
  • Inflammation
  • Infection or abscess formation
  • Tumors of the sac or related glandular tissues

    What to Watch For

    Signs of anal gland or anal sac problems in dogs may include: 

  • Scooting or dragging the anus on the ground or carpet
  • Frequent licking of the anus or tail base
  • Reluctance to sit or sitting asymmetrically to avoid pressure on the painful anal sac
  • Straining to defecate, difficulty defecating, production of ribbon-like stools
  • Painful swelling at the 4 o’clock or 8 o’clock locations around the anus

    Similar signs can be seen in dogs with a different disease called perianal fistula, a severe condition that causes draining tracts around the anus. The breeds that most commonly develop perianal fistulae are German shepherd dogs and Irish setters.

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    Diagnosis of Anal Sac Disease in Dogs

    Diagnostic tests may be required to confirm the diagnosis and exclude other diseases causing similar signs. Tests may include:

  • A complete history and physical exam
  • Rectal examination, including an attempt to manually express (empty) the anal sacs – this could require sedation.
  • Blood tests (anal sac tumors can cause an increase in blood calcium levels)
  • If a tumor is found, chest and abdominal X-rays to check for tumor spread to other organs (lungs, lymph nodes) and an abdominal ultrasound to check lymph nodes for tumor spread
  • Treatment of Anal Sac Disease in Dogs

    For simple impactions and cases of inflammation, expressing the anal sacs may be all that is necessary. If the anal sacs cannot be expressed while your pet is awake, then anesthesia may be necessary to express and flush the anal sacs. Other treatments may include:

  • Antibiotics or anti-inflammatory drugs may be given orally or infused into the sacs if necessary.
  • Chronic cases of impaction or inflammation may require surgical removal of the anal sacs.
  • Abscesses of the anal sacs are lanced and flushed, and then treated with oral antibiotics.
  • Tumors of the anal sacs are treated by complete removal of the affected sac. Affected lymph nodes can also be removed, although this is more difficult.
  • In-depth Information on Anal Sac Disease in Dogs

    The anal sacs are located at the 4:00 and 8:00 positions around the anus, embedded in the muscle of the anal sphincter (the muscle that closes the anus). Related glands produce a pungent yellowish secretion during defecation.

    Common types of anal gland problems in dogs include: 

  • Anal Sac Impaction. This disease 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 or even infected. 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.
  • Anal Sacculitis. 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 pus-filled anal sac results from a bacterial infection. Anal sac abscesses are more painful than anal sac impactions. 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 Tumors(“apocrine gland adenocarcinomas”). These 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 (lower back) 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 (“scooting,” excessive licking, straining to defecate, reluctance to sit, or sitting asymmetrically).
  • Perianal Fistulas. This is a severe condition of the tissue around the anus, creating fistulas, or draining/oozing tracts, around the anus. It is most commonly seen in German shepherds, and is also seen in Irish setters. The cause of this difficult to control disease is unknown, but is currently thought to have an immune-mediated origin (which means that the dog’s immune system is for some unknown reason attacking the tissues around the anus). German shepherds and Irish setters with symptoms of anal sac disease should also be screened for this more serious disease.
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