Narrowing of Anal or Rectal Opening in Dogs

Rectal stricture occurs when scar tissue obstructs the free passage of bowel movements through a dog’s anal cavities. This can arise most likely from causes of neoplasia, (abnormal or tumorous  growth), injury from wounds from foreign objects (such as wounds or a bite mark) or from the swallowing of indigestible objects (bones and toys), and proctitis (severe inflammation), causing distress and pain.

Rectal strictures can be defined as the narrowing of the anal and rectal cavities resulting from a variety of complications that include trauma (from surgery or injury), ingesting foreign objects, cancer, inflammation from infection, and digestive disorders. These conditions can result in the obstruction of the anal canal and chronic pain.

• Difficulty and painful sitting  
• Struggling with bowel movements
• Hematochezia (anal bleeding and bloody stools)
• Abnormally small or ribbon like feces
• Dyschezia (difficulty defecating that is usually caused by a willful intention to resist passing stools)
• Constipation
• Diarrhea
• Behavioral distress (agitation, not wagging their tail, or being reluctant for others to get near the areas of sensitivity)

Types

Anal strictures are extremely rare but are known to be most prevalent in older dogs (7 years or above) and in Beagles, Poodles, and German Shepherds. Typically, it is extremely important to identify the different types of strictures that could cause this condition as it pertains to cancer, as detecting the disease during its early stages may give leeway to successful treatment and survival.  A biopsy should be done to identify benign and malignant neoplastic growth. Other wounds that require surgery could include the removal of foreign objects including items such as toys, rocks, and chicken bones that cause severe proctitis or inflammation. The most common cause of proctitis is colitis.  The colon can easily become inflamed due to a number of disorders, which include parasitic infections of the intestines, tapeworms, and inflammatory bowel disease.

• Injuries such as cuts, scrapes, wounds, lesions, or abscess that occurs in the parameter of the area
• Foreign objects (especially bones) trapped in the passage of the area
• Perianal fistula (a lesion that affects the skin surrounding the anus)
• Parasitic or fungal infections
• Surgery
• Neoplastic (tumor growth)
• Cancer
• Chronic proctitis (severe inflammation)

A veterinarian will conduct a physical examination of your dog, noting previous injuries and the history of past and present symptoms.  He will be able to note inflammation of the affected areas and indicate the central areas of pain within the body that could include the abdomen and anal area, by applying gentle pressure and assessing your pet’s reflexes. A routine complete blood count and urine sample will be conducted.  X-rays are extremely useful, including barium enema contrast radiology (to examine the large intestine, colon and rectum), as is digital rectal palpation.  A biopsy may be conducted to eliminate the possibility of cancer or tumor growth.  This can be done by endoscopy, with a camera being inserted through the cavities to view and photograph the extent of the damage as well as obtaining a tissue sample to be examined and evaluated to determine infection or cancerous growth.      

High fiber nutrition and diet, along with the use of stool softeners or laxatives such as miralax or lactulose are useful to help foods pass freely. An enema may be done to clear and clean any blockage. Medications such as pain relievers and anti-inflammatories (corticosteroids) will be given to reduce discomfort. If your dog has a parasitic or bacterial infection, the use of antifungals or antibiotics will be given to counter the infection.

Balloon dilation therapy is a very common technique to correct the abnormally small structure of the rectal opening by widening it, as this is known to have the least amount of risks. Using a fluoroscopy or endoscopy, the balloon dilator is placed into the center of the stricture and is inflated by using sterile saline and with triamcinolone (steroids used to counter inflammation) injections. This may be done multiple times, to ensure widening and enlargement.

Surgery is an option in attempting to remove both benign and malignant tumors or strictures within the intestinal and rectal cavities. However, surgery such as endorectal pull-through (where the diseased mucous membrane is removed from the lower bowel, and reattached from the end of the injured neuron to regenerate), allows the anus to retain function. Chemotherapy and radiation therapy may be required to eliminate malignant tumors.

The prognosis of malignant tumors or cancer in dogs is dire. Many dogs succumb to the illness in as early as 1 to 2 months after diagnosis. Chemotherapy or radiation therapy may be an option to preserve the quantity of life, but not the quality. Surgery is an outcome that comes with complications that include incontinence and reforming of scar tissue. The use of balloon dilation therapy usually produces good outcomes for strictures that are not severe, though the procedures may be necessary to be repeated multiple times (from 2 and up to 6). Side effects can include tears, hemorrhaging, and infection, so vigilant monitoring and follow-up prognosis should be closely examined.