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30 Adenocarcinoma, Intestinal/Colonic

an essential component to a complete Technician Tips SUGGESTED READING
wellness exam. • Owners can confuse stranguria with tenes- Turek M, et al: Perianal tumors. In Withrow S, Vail
VetBooks.ir polyuria/polydipsia without an owner gland adenocarcinoma, the latter is more AUTHOR: Joanne L. Intile, DVM, MS, DACVIM
mus. Although both may be seen with anal
• Sometimes, dogs are presented for signs of
D, Page R, editors: Small animal clinical oncology,
ed 5, St. Louis, 2013, Saunders, pp 423-431.
frequently observed. Careful inquiry as
observation of rectal disease.
owner’s observations can aid in differentiating
between the two signs. EDITOR: Kenneth M. Rassnick, DVM, DACVIM

Adenocarcinoma, Intestinal/Colonic Client Education
Sheet

BASIC INFORMATION PHYSICAL EXAM FINDINGS • Ultrasonography can define primary mass
• Palpable abdominal mass and lymphadenomegaly or suggest organ
Definition • Palpable mass and/or bleeding on rectal metastasis and may guide fine-needle aspira-
Malignant tumor arising from gastrointestinal examination tion (p. 1112).
(GI) tract epithelium • Abdominal effusion from carcinomatosis or
peritonitis Advanced or Confirmatory Testing
Epidemiology • Signs of anemia Endoscopic or surgical biopsy, or aspiration
SPECIES, AGE, SEX • Poor body condition cytology, is required for definitive diagnosis.
Intestinal adenocarcinoma is rare in dogs and Choice of approach depends on location of
cats, accounting for 1% of tumors in necropsied Etiology and Pathophysiology the lesion; colonoscopy is preferred over surgery
cats and 0.1% of tumors in dogs. Colorectal Genetic predisposition is likely. for colonic neoplasia, but endoscopy (p. 1098)
adenocarcinoma is slightly more common than may be nondiagnostic for jejunal lesions (unable
intestinal. DIAGNOSIS to reach the lesion).
• Mean age of cats with small intestinal adeno-
carcinoma is 11 years; colorectal tumors in Diagnostic Overview TREATMENT
cats occur at a mean age of 16 years. The diagnosis is suspected in patients with GI
• Mean age of dogs with intestinal and signs that fail to respond to conservative therapy, Treatment Overview
colorectal adenocarcinomas is 9 years. evidence of an intestinal mass, or both. Diag- Surgical resection is the preferred treatment
nostic imaging is essential for identifying a for intestinal and colonic adenocarcinoma.
GENETICS, BREED PREDISPOSITION lesion, although results vary. Lesions must be Additional measures such as chemotherapy or
• Intestinal adenocarcinoma is most common sampled for histopathology or cytology to radiation therapy may be warranted, and con-
in boxers, collies, poodles, West Highland confirm the diagnosis. sultation with an oncologist is recommended.
white terriers, German shepherds, and
Doberman pinschers, and Siamese cats (70% Differential Diagnosis Acute General Treatment
of feline small intestinal adenocarcinomas Depends on lesion location and signs: General supportive care includes
occur in Siamese). • Foreign body • Rehydration and restoring electrolyte
• Shar-peis may have increased incidence of • Intussusception homeostasis
intestinal adenocarcinoma. • Infectious enteropathy, chronic parasitism • Managing anemia with transfusions and
• In dogs, colorectal tumors are most common • Inflammatory bowel disease hematinics as indicated
in collies and German shepherds. • Alimentary lymphoma • Antibiotic and emergency management for
• Alimentary mast cell tumor in cats peritonitis (p. 779)
ASSOCIATED DISORDERS • Colorectal polyps, adenomas • Analgesics for pain in obstructive lesions or
• Intestinal obstruction • Smooth muscle tumors (leiomyoma, leio- peritonitis
• Melena myosarcoma, GI stromal tumor) • Promotility agents are contraindicated in
• Hematochezia obstructive disease.
• Anemia Initial Database
• CBC results often are nonspecific: neutro- Chronic Treatment
Clinical Presentation philia; regenerative, nonregenerative, or • Curative therapy for nonmetastatic intestinal
HISTORY, CHIEF COMPLAINT microcytic anemia secondary to blood loss and colonic adenocarcinoma is complete
• Clinical signs depend on lesion location: • Serum biochemistry panel: elevation of surgical excision.
intermittent vomiting, hematemesis, alkaline phosphatase, hypoalbuminemia/ • Even with metastatic disease or carcinoma-
anorexia, dehydration, melena, hematochezia, hypoproteinemia possible, increased blood tosis, survival times are extended by surgical
diarrhea, signs of intestinal obstruction or urea nitrogen (BUN) if GI bleeding resection of obstructive lesions in cats with
peritonitis, abdominal distention from • Urinalysis: usually unremarkable intestinal adenocarcinoma.
peritoneal effusion due to carcinomatosis. • Thoracic radiographs for metastasis • Radiation therapy may be palliative or
• Colorectal adenocarcinomas cause hemato- • Abdominal radiographs may demonstrate curative for nonresectable colonic lesions.
chezia, tenesmus, and dyschezia. signs of intestinal obstruction, mass effect, • Chemotherapy is usually unsuccessful, but
• Slowly progressive, non-obstructive tumors or may be noncontributory. therapy with nonsteroidal antiinflammatory
may cause anorexia, weight loss, and iron- • Positive contrast GI study or barium enema drugs, doxorubicin, platinum agents, and
deficiency anemia. may reveal mass or annular constrictive lesion. antimetabolites (gemcitabine, fluorouracil)

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