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Small intestine: neoplasia



  • The intestines are a rare site of neoplasia in the dog; account for 8% of all malignancies.
  • Sites: mainly in the jejunum and ileum.
  • Cause: most important histological types are adenocarcinoma and lymphoma.
  • Signs: variable depending on type of tumor present. From chronic diarrhea and weight loss to signs of obstruction.
  • Diagnosis: radiography, ultrasound, or CT scan. Cytology and/or histopathology.
  • Treatment: resection of adenocarcinomas and sarcomas. Chemotherapy for lymphoma.
  • Prognosis: poor for lymphoma, guarded for adenocarcinoma.



  • None known.


  • Leiomyoma.
  • Adenomatous polyp.



  • Variety of presentations.
  • Ulceration common with adenocarcinoma, leading to hypoproteinemia Hypoproteinemia.
  • Complete obstruction or perforation leading to peritonitis Peritonitis → adenocarcinoma.
  • Benign and malignant lesions are equally likely to cause severe complications.
  • Rarely, some tumors, eg mast cell tumors may release biologically-active agents such as histamine → cutaneous changes or acute diarrhea.
  • Diffuse or infiltrating tumors, eg lymphoma Lymphoma → disturbed motility and malabsorption → weight loss, hypoproteinemia or intermittent diarrhea.
  • Metastatic disease to mesenteric lymph nodes, liver, spleen, omentum, lungs.
  • Metastatic rate of GIST 7% and up to 50% for adenocarcinoma.


  • Chronic or acute.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Dailey D D, Ehrhart E J et al (2015) DOG1 is a sensitive and specific immunohistochemical marker for diagnosis of canine gastroinestinal stromal tumors. J Vet Diagn Invest 27 (3), 268-277 PubMed.
  • Willard M D (2012) Alimentary neoplasia in geriatric dogs and cats. Vet Clin Small Anim 42 (4), 693-706 PubMed.
  • Gieger T (2011) Alimentary lymphoma in cats and dogs. Vet Clin Small Anim 41 (2), 419-432 PubMed.
  • Dominguez P A, Dervisis N G et al (2009) Combined gemcitabine and carboplatin therapy for carcinomas in dogs. JVIM 23 (1), 130-137 PubMed.
  • Kaneko N, Yamamoto Y, Wada Y et al (2009) Application of polymerase chain reaction to analysis of antigen receptor rearrangements to support endoscopic diagnosis of canine alimentary lymphoma. J Vet Med Sci 71 (5), 555-559 PubMed.
  • Rassnick K M, Moore A S et al (2009) Efficacy of combination chemotherapy for treatment of gastrointestinal lymphoma in dogs. J Vet Intern Med 23 (2), 317-322 PubMed.
  • Spugnini E P, Gargiulo M et al (2008) Adjuvant carboplatin for the treatment of intestinal carcinoid in a dog. In Vivo 22 (6), 759-761 PubMed.
  • Frank J D, Reimer S B et al (2007) Clinical outcomes of 30 cases (1997-2004) of canine gastrointestinal lymphoma. JAAHA 43 (6), 313-321 PubMed.
  • Maas C P, ter Haar G, van der Gaag I, Kirpensteijn J (2007) Reclassification of small intestinal and cecal smooth muscle tumors in 72 dogs: clinical, histologic, and immunohistochemical evaluation. Vet Surg 36 (4), 302-313 PubMed.
  • Russell K  N, Mehler S J et al (2007) Clinical and immunohistochemical differentiation of gastrointestinal stromal tumors from leiomyosarcomas in dogs: 42 cases (1990-2003). JAVMA 230 (9), 1329-1333 PubMed.
  • Sako T, Uchida E, Okamoto M et al (2003) Immunohistochemical evaluation of a malignant intestinal carcinoid in a dog. Vet Pathol 40 (2), 212-215 PubMed.
  • Paoloni M C, Penninck D G & Moore A S (2002) Ultrasonographic and clinicopathologic findings in 21 dogs with intestinal adenocarcinoma. Vet Radiology & Ultrasound 43 (6), 562-7 PubMed.
  • Takahashi T, Kadosawa T, Nagase M, Matsunaga S, Mochizuki M, Nishimura R, Sasaki N (2000) Visceral mast cell tumors in dogs: 10 cases (1982-1997). JAVMA 216 (2), 222-226 PubMed.
  • Crawshaw J, Berg J et al (1998) Prognosis for dogs with nonlymphomatous, small intestinal tumors treated by surgical excision. JAAHA 34 (6), 451-456 PubMed.

Other sources of information

  • Vail D M, Withrow S J, Page R L (2013) Cancer of the gastrointestinal tract. In: Small Animal Clinical Oncology. Withrow S J & MacEwen E G (eds). 5th edn. Philadelphia: W B Saunders Co., pp 412-423.
  • (1996) The small intestine. In: BSAVA Manual of Canine & Feline Gastroenterology. J W Simpson, E Hall & D Thomas (eds). BSAVA Cheltenham. p 153.
  • (1996) Neoplasms of the gastrointestinal tract. In:Strombeck's Small Animal Gastroenterology. 3rd edn, W B Saunders, Philadelphia. p 519.
  • Head K W & Else R W (1981) Neoplasia and allied conditions of the canine small intestine. Veterinary Annual 21st Edition. pp 190-207.

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