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Gastrointestinal: neoplasia



  • Primary tumors of the gastrointestinal (GI) tract are rare except lipomas in old horses.
  • Gastric squamous cell carcinoma and alimentary lymphosarcoma are the most common primary neoplasms of the gastrointestinal tract.
  • Presentation and clinical signs will depend on the location of the lesion(s); clinical signs can include discomfort associated with the peritoneal cavity and/or GI tract, with weight loss and diarrhea being common presenting signs.
  • Some gastric neoplasia will show signs of a paraneoplastic syndrome as the initial clinical presentation.
  • Upper gastrointestinal tract lesions may have obvious space occupying effects such as dysphagia and coughing, although inappetence is the most common clinical sign.
  • Occasionally invades the peritoneal cavity.
  • Clinical signs of abdominal tumors are usually non-specific, insidious in onset and progressive:
  • Diagnosis largely depends on laboratory evaluation but will be assisted by a complete gastrointestinal physical examination Gastrointestinal: physical examination including rectal palpation Musculoskeletal: rectal palpation and ultrasonography.
  • Abdominocentesis Abdomen: abdominocentesis can prove useful, as some horses will have neoplastic cells within the peritoneal fluid. However, a negative result does not rule out the presence of neoplasia.
  • Treatment is generally unsuccessful for intra-abdominal or multicentric tumors, however localized lymphomas may be amenable to treatment.
  • Prognosis is usually grave.

Neoplasia - general

See Intestinal neoplasia: tumor types table.


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Diagnostic techniques

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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Santschi E M (2012) Equine colic caused by neoplasia. Equine Vet Educ 24 (9), 437-438.
  • Hollis A R (2011) Paraneoplastic syndromes. Equine Vet J 23 (4), 184-184.
  • Taylor S D, Haldorson G J et al (2009) Gastric neoplasia in horses. J Vet Intern Med 23, 1097-1102.
  • Taylor S D, Pusterla N et al (2006) Intestinal neoplasia in horses. J Vet Intern Med 20, 1429-1436.
  • Henson F M D & Dobson J M (2004) Use of radiation therapy in the treatment of equine neoplasia. Equine Vet Educ 16 (6), 315-318.
  • East L M, Savage C J & Traub-Dargatz J L (1999) Weight loss in the horse - a focus on abdominal neoplasia. Equine Vet Educ 11 (4), 174-178.
  • Coumbe K M (1994) Primary parotid lymphoma in a 10 year old Hanoverian gelding. Equine Vet Educ 6, 91-94.
  • Blackwood L & Dobson J M (1994) Radiotherapy in the horse. Equine Vet Educ 6, 95-99.
  • Marr C M (1994) Clinical manifestations of neoplasia. Equine Vet Educ 6, 65-71.
  • Hillyer M H (1994) The use of ultrasonography in the diagnosis of abdominal tumors in the horse. Equine Vet Educ 6, 273-278.
  • Proudman C J & Baker S J (1994) Gastric disease in the adult horse - a clinical perspective. Equine Vet Educ 6, 178-184.
  • Reid S W & Howie, F (1992) Factors associated with neoplastic disease in the horse. Equine Vet Educ 4, 66-68.
  • Olsen S N (1992) Squamous cell carcinoma of the equine stomach - a report of five cases. Vet Rec 131 (8), 170-173 PubMed.
  • Mair T S & Hillyer M H (1991) Clinical features of lymphosarcoma in the horse - 77 cases. Equine Vet Educ 4, 108-113.
  • Church S, West H J & Baker J R (1987) Two cases of pancreatic adenocarcinoma in horses. Equine Vet J 19, 77-79 PubMed.

Other sources of information

  • Hollis A R (2015) Paraneoplastic Syndromes. In: Current Therapy in Equine Medicine. 7th edn. Eds: Sprayberry K A & Robinson N E. Elsevier Saunders, Missouris, USA. pp 415-417.
  • Knottenbelt D C, Patterson-Kne J C & Snalune K L (2015) Clinical Equine Oncology. Elsevier, London, UK.
  • East L M & Savage C J (1998) Abdominal Neoplasia (Excluding Urogenital Tract). Vet Clin North Am Equine Pract 14, 475-493.

Related Images


Abdomen: abdominocentesis

Abdomen: laparoscopy

Abdomen: laparotomy

Abdomen: lipoma - pedunculated

Abdomen: pain - adult

Abdomen: peritonitis

Anemia: chronic disease

Anemia: overview

Anesthesia: general - overview

Blood: biochemistry - albumin

Blood: biochemistry - alkaline phosphatase (SAP, ALP)

Blood: biochemistry - aspartate amino transferase (AST)

Blood: biochemistry - calcium

Blood: biochemistry - gamma globulins

Blood: biochemistry - gamma glutamyl transferase (gGT)

Blood: biochemistry - glucose

Blood: biochemistry - sorbitol dehydrogenase

Blood: biochemistry - total protein

Blood: eosinophils

Blood: hemoglobin (Hb) concentration

Blood: lymphocytes

Blood: neutrophils

Blood: overview


Cardiovascular: blood pressure monitoring

Cecum: impaction

Cecum: intussusception - cecocecal / cecocolic

Cecum: torsion

Colon: displacement - pelvic flexure

Colon: impaction

Colon: infarction - non-strangulating

Colon: small - obstruction

Diarrhea: idiopathic

Endocrine: hypoadrenocorticism


Facial nerve: trauma

Gastrointestinal endoscopy

Gastrointestinal: enterolith

Gastrointestinal: epiploic foramen hernia

Gastrointestinal: fecalith / bezoar

Gastrointestinal: nasogastric intubation

Gastrointestinal: neoplasia - melanoma

Gastrointestinal: physical examination

Gastrointestinal: small intestine - intussusception

Gastrointestinal: small intestine - torsion

Gastrointestinal: stricture

Gastrointestinal: tympany/flatulent colic

Ileum: impaction

Intestine: enteritis

Liver: hepatitis - chronic active

Lymphosarcoma: overview

Musculoskeletal: rectal palpation

Peritoneal fluid: cytology

Plasma: fibrinogen

Protein-losing conditions


Skin: fibroma / fibrosarcoma

Skin: neoplasia - lymphosarcoma

Skin: neoplasia - mast cell tumor

Skin: neoplasia - melanoma

Skin: neoplasia - squamous cell carcinoma

Strongyle infestation: large

Tapeworm infection

Toxicity: pyrrolizidine alkaloid

Ultrasonography: abdomen

Umbilicus: hernia (strangulating)

Urine: overview

Urogenital: rectal palpation

Vesicular stomatitis

Weight loss: overview

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