Dog Health & Care

Canine Anorectal Diseases – What Are They and What to Do About Them

Canine anorectal diseases relate to illnesses or medical problems of a dog’s rectum and anus. Anorectal diseases will have some type of deformation in this area, with anal sac disease one of the most common diseases in the dog’s anal region.

Dogs with a tendency for anorectal diseases are over seven years old, what is considered middle age to elderly. It is considered to be an older dog disease, excluding imperforate anus. That would be a newborn puppy disease when it is born without an anus.

canine anorectal diseases

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Types of canine anorectal diseases

There are many types of canine anorectal diseases, and most focus on the rectum or anus area. Both areas are in the final stages of the digestive region: the rectum is the segment of the large intestine before ending at the anus; and the anus is the dog’s opening that regulates the elimination of feces. The anus is considered the major problem area of the two.

  • ANAL BLEEDING – this can be caused by many different diseases or colon disorders, rectum or gastrointestinal tract disorders or diseases, anorectal disease, rectal prolapse, intestinal parasites or colonic ulcers.
    • A similar situation is hematochezia or HCT when bright red blood is in the stools. Sometimes this is connected to diseases of the colon.
    • In a young puppy, bloody stools are first checked out as parvo. Dogs with Parvo will vomit, have diarrhea, lethargy, loss of appetite and blood in stools.
    • Symptoms of anal bleeding:
      • Excessive hard stools or diarrhea will irritate the dog’s inflamed colon tissue and rectum.
      • This causes the area to rip and tear.
      • Chronic diarrhea in the affected dog has mucus and blood in it.
      • Any irritation and ulceration of the colon leads to repeated vomiting, leading to serious weight loss because of a lack of appetite. This condition is called Hemorrhagic Gastroenteritis (HGE)
Canine anorectal diseases
Credit: American College of Veterinarian Surgeons (symptom of anal cancer)
  • ANAL CANCER (gland/sac) – a rare form of cancer, it is usually malignant.
    • Tumors in the anal sac or gland are serious because they invade surrounding tissues.
    • Tumors usually develop on one side, not both.
    • In approximately 1/4 of the cases, these tumors elevate blood calcium [Note: called hypercalcemia] which can cause kidney failure.
    •  Anal cancer occurs in males and females equally.
    • Anal cancer occurs in all dog breeds, but the numbers are higher in Spaniels.
    • Dogs who get anal cancer average at 10 years of age.
    • Symptoms of anal cancer
      • External swelling in the area around the anus [Note: perianal region].
      • The tumor or mass is felt during a routine rectal examination.
      • Constipation develops due to the blockage of the tumor.
      • Painful straining when passing a stool.
      • Blood is seen in the stool.
      • Elevated calcium levels cause excessive thirst and urination is possible kidney failure is developing.
      • Large tumors may produce limited symptoms when passing stools without the presence of enlarged lymph nodes in the abdomen.
  • ANAL FISTULA – this affects dogs who are over 7 years of age;  characterized by chronic, purulent, malodorous, ulcerating, sinus tracts in the perianal (anus) tissues.
    • Other names – Perianal Sinus, Anusitis, Anorectal Abscess, Pararectal Fistula, Furunculosis
    • Small oozing lesions in a dog’s skin on the sides of the anus.
    • As it worsens, tunneling holes develop in the skin and deeper tissues that surround the anus area.
    • If left untreated, these formations become wider and deeper, sometimes surrounding the entire anus circumference.
    • Like anal cancer, all dogs can develop this disease but German Shepherds are most susceptible.
    • As the tail hangs low and continuously slides back and forth across the anus area, it is thought to be a major factor for the condition.
    • Dogs with anal fistula have concurrent diarrhea because of inflammatory bowel disease.
      • Many veterinarians feel these two conditions, anal fistula and inflammatory bowel disease, are related.
    • Symptoms of canine anal fistula
      • Painful straining and passing of stools when the condition first develops
      • Affected dogs may have concurrent chronic diarrhea because of inflammatory bowel disease; in fact, the two conditions may be related. This disease shows many similarities to Crohn’s disease in people.
      • You will see your dog scooting across the floor on its butt. This could be for several reasons: gland or sac issues around the anus; the beginning stages of anal fistula; or even food allergies.
  • ANAL STENOSIS – when the rectum or anus of a dog is constricted, causing the expelling of feces serious problems. Also called rectal stricture
    • Anal Crohn’s disease mimics the symptoms of anal stenosis
    • Cancer growths can be the cause, injuries in the area or scar tissue because of inflammation. But there are many other causes:
      • Complications resulting from a surgical procedure
      • Overuse of laxatives
      • Severe blood infection (sepsis) that affects organs in the body
      • Loss of blood to a particular area of the body
      • AIDS and venereal diseases
      • Infection caused by the amoeba entamoeba histolytica
      • Inflammatory bowel disease (IBD)
      • Disorder or inflammation of the colon and small intestine
    • Symptoms of anal stenosis
      • Constipation
      • Painful bowel movements
      • Stools that are difficult to expel, are narrow, and break apart like pellets
      • Evidence of bright red blood in the toilet (rectal bleeding)
  • MEGACOLON – this is a term used in the medical field for dilated, flaccid, and incompetent colons; it is uncommon; and acquired in older dogs
    • Other names are: Subtotal Colectomy, Colectomy, Feline Megacolon
    • Megacolon is secondary to chronic constipation and retention of feces
    • This could be a congenital dysfunction or acquired, not a specific disease entity
    • Results in obstipation, meaning the inability to defecate
    • Feces is retained in the colon, which is a larger diameter of feces than can pass through the pelvis
    • Due to its large size and the fact the colon absorbs water, the feces will become dry and hard.
    • Surgery may be required, once other medical treatments are exhausted
    • Tumors, strictures, and hernias of the rectum/anus can also contribute to the development of megacolon or constipation.
    • Symptoms of canine megacolon
      • Constipation
      • Obstipation
      • Infrequent elimination
      • Straining to eliminate
      • Vomiting
      • Loss of appetite
      • Extremely dilated in size
  • HEMORRHOIDS – Hemorrhoid (piles) – dogs do not get hemorrhoids due to their anal sacs lubricating difficult stools. Humans do not have anal sacs.
  • IMPERFORATE ANUS – sometimes puppies are born without an anus.
  • PROCTITIS – inflammation of the colon or rectum


Symptoms of canine anorectal diseases

  • The dog will scoot across the floor on its butt
  • Swelling and redness around the anus when the condition develops
  • The dog will lick or chew in the anal area, or under its tail
  • An extremely foul odor when leakage begins on the left, right or both sides of the anus


Canine Anorectal Diseases
Image provided by Nancy Houser of Liza Doolittle

Treatments for Canine Anorectal Diseases

I have a seven-year-old little chihuahua, Liza Doolittle, who has developed chronic anal fistula issues. She will act depressed when the symptoms start, licking the area even though there seems to be nothing there. She wants to be held and cuddled more than usual, as she does not feel well. This is the time I start putting my antibiotic ointment onto the area, rubbing it in very soft and gently. It hurts, so she does not like but it has to be done. Afterward, I love her up and give her a treat, usually a Dream Bone for small dogs. I do this every 12 hours apart until it breaks on its own, repeating the antibiotic until the area clears.

Without treatment, if it does not break on its own, you will need to see a vet before it ruptures or tears. However, this treatment has always worked for me, along with a very warm cloth held to the affected area before I apply the antibiotic ointment. You can use antibiotic creme, as it applies better, but it will not stay on as long. You will need to apply it every four to six hours apart.


In dogs, diet is extremely important as the condition is affected. In fact, it is a vital local factor that affects colon function and the quality of feces within the colon. Our next article will discuss the importance of diet for canine anorectal diseases.



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