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Rectal and Anal Prolapse in Dogs

The rectum is the terminal end region of the large intestine, with the anus serving as an extension of the rectum, opening to allow digestive waste to leave the body. Anal or rectal prolapse is a condition in which one or more layers of the rectum are displaced through the anus, the opening which allows digestive waste to leave the body. It can be caused by a variety of factors, including disorders of the digestive, urinary, or genital systems.

Although dogs of any gender, age, or breed may be affected by this condition, those viral or worm infections are at increased risk. If you would like to learn how these disorders affect cats, please visit this page in the PetMD health library.

Symptoms and Types

Rectal prolapse occurs when all layers of the anal/rectal tissue, along with the rectal lining, protrude through the external anal opening. The protrusion of the rectal lining through the external anal opening, meanwhile, is solely referred to as anal prolapse.

Dogs with rectal prolapse will demonstrate persistent straining while passing stool (or defecating). In an incomplete prolapse, a small portion of the lining of the rectum will be visible during excretion, after which it will subside. In a complete prolapse, there will be a persistent mass of tissue protruding from the anus. In the chronic stages of complete prolapse, this tissue might be black or blue in appearance.

Causes

A dog may develop rectal or anal prolapse if it strains while passing stool, or if it undergoes surgery to the lower digestive organs. Other contributing factors for these two conditions include:

• Disorders of the digestive system that cause diarrhea, straining while passing stools, presence of worms or other parasites in the digestive system, and inflammation of the small or large intestines
• Disorders of the urinary and genital systems, such as inflammation or enlargement of the prostate, inflammation of the bladder, urinary stones, and abnormal labor or birthing process
• Chronic constipation, presence of sac-like protrusions in the intestine, rectal or anal tumors, or deviation of the rectum from its usual position

Diagnosis

Your veterinarian will perform a complete physical examination of your dog, including a chemical blood profile and a complete blood count. The results will usually return normal, though there may be high levels of white blood cells, similar to that seen when an infection is present. A test of stools samples may reveal the presence of parasites.

Further diagnostic procedures include X-rays or ultrasounds of the abdominal area, which may demonstrate a large prostate, foreign bodies, thickening of the bladder walls, or kidney stones.

Your doctor will also conduct a manual rectal examination to feel for displaced tissue masses. During pathological examination of the tissue (for biopsy), it may appear swollen, and will ooze red blood when incised. The tissue, if dead, appears dark purple or black and oozes bluish blood when incised.