Anorectal disease: Tumors best treated by complete surgical excision - DVM
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Anorectal disease: Tumors best treated by complete surgical excision


Tumors of the rectum are likely to have a multitude of inciting causes. Rectal tumors are best treated by complete surgical excision. Good to excellent results are generally obtained with resections of rectal polyps or carcinoma in situ. Recurrences occur in only a few cases. Radical full-thickness resection of adenocarcinomas has been recommended, but dogs undergoing cryosurgery and local excision may have a better outcome. Wound dehiscence, infection, rectal stricture and fecal incontinence are significant complications associated with radical excision. The prognoses for rectal polyps, carcinoma in situ, leiomyomas and fibromas are generally favorable. Adenocarcinomas, lymphosarcomas and plasmacytomas tend to recur. Dogs with annular colorectal adenocarcinomas have a particularly poor prognosis with average survival time of only 1.6 months.

Perianal fistula

Perianal fistula, or anal furunculosis, is a chronic debilitating condition of dogs characterized by single or multiple ulcerated sinuses that can involve up to 360 degrees of the perianal tissue. True fistulous tracts from the anorectal canal to the perianal skin are uncommon in the dog, yet the term perianal fistula has persisted. Dogs with perianal fistula are typically presented with tenesmus, dyschezia, fecal incontinence, licking of the anal area, anal bleeding, constipation and/or a malodorous anorectal discharge. Anorexia and weight loss also can occur in some dogs with severe ulceration or infection. Large-breed dogs are most commonly affected, with the highest incidence in German Shepherds and Irish Setters. Physical examination of the anorectum may require sedation or anesthesia in some dogs because of extreme pain. Examination usually reveals single or multiple areas of ulceration, fistulous tracts and a purulent exudate with frank hemorrhage. Anorectal palpation may reveal multiple rectocutaneous fistulas and anal stenosis.

Ruptured anal sac abscess and perianal adenocarcinoma are the only important differential diagnoses. Anal sac rupture is usually seen as a unilaterally draining tract located ventrolateral to the anus. The cellulitis and fistulation associated with anal-sac rupture is usually less extensive than with perianal fistula. The anal sacs may also be involved in animals affected with perianal fistula, rendering definitive diagnosis difficult. Perianal adenocarcinoma usually has a proliferative raised appearance, although ulceration is common, and they may grossly resemble perianal fistula.

Severe cases generally require both medical and surgical management. The principles of medical management include removal of perineal hair, cleansing and debridement; antibacterial therapy; immunosuppressive therapy; and dietary therapy. Novel antigen diets may affect clinical improvements in some cases, but complete resolution generally requires the concurrent use of immunotherapy. Immunosuppression with azathioprine, cyclosporine or tropical tacrolimus has proved useful in inducing remission in severely affected cases. Thereafter, periodic use of the immunosuppressive drugs may be required for control.

What's your question? Send your pediatric/geriatric related questions to: Pediatric/Geriatric Protocol, DVM Newsmagazine , 7500 Old Oak Blvd., Cleveland, OH 44130. Your questions will be answered by Dr. Hoskins in upcoming columns.

Dr. Hoskins is owner of DocuTech Services. He is a diplomate of the American College of Veterinary Internal Medicine with specialities in small animal pediatrics. He can be reached at (225) 955-3252, fax: (214) 242-2200, or e-mail:


Source: DVM360 MAGAZINE,
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