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Endoscopy Essentials, Gastroenterology, Radiology/Imaging

Overview of Upper Gastrointestinal Endoscopy

Overview of Upper Gastrointestinal Endoscopy


Julie Callahan Clark, DVM, Diplomate ACVIM

Welcome to our newest column in Today’s Veterinary PracticeEndoscopy Essentials. Similar to the approach of our Imaging Essentials column, which addresses imaging by anatomic location, each article in this column will discuss endoscopic evaluation of a specific body system, reviewing indications, disease abnormalities, and proper endoscopic technique. Endoscopy Essentials articles will be archived at tvpjournal.com, allowing readers access to the entire series as it is published.

Upper gastrointestinal endoscopy (UGIE) is a minimally invasive procedure that can aid in the diagnostic evaluation of clinical signs referable to the esophagus, stomach, and proximal small intestine. UGIE is commonly pursued to obtain biopsy samples as part of the diagnostic evaluation of a pet with chronic gastrointestinal (GI) signs.



Esophagoscopy is routinely performed as part of a UGIE; it is:

  • Most useful for diagnosis of processes that disrupt either the esophageal mucosa or obstruct its lumen, such as esophagitis, stricture, foreign body, or mass
  • Utilized to confirm the presence of, or provide additional evidence for, other esophageal diseases, including megaesophagus, esophageal diverticula, vascular ring anomalies, and hiatal hernias
  • Employed for therapeutic procedures, such as foreign body retrieval and treatment of esophageal strictures.

Initial Evaluation

Clinical Signs. Clinical signs that raise the suspicion for esophageal disease include regurgitation, dysphagia, hypersalivation, cough, and weight loss.

Diagnostics. Preliminary diagnostic evaluation should include 3-view thoracic radiographs. If a motility disorder is suspected, pursue a contrast esophagram prior to esophagoscopy.

Normal Appearance

The normal esophageal mucosa is pale pink, smooth, and glistening (Figure 1).

  • The cat’s caudal thoracic esophagus has circular rings, which denote the section comprised of smooth muscle.
  • Longitudinal mucosal folds, which disappear when the lumen is fully insufflated, are encountered in the canine cervical esophagus.
  • In both species, the outline of the trachea in the ventral wall of the cervical esophagus and outline of the aorta in the midthoracic esophagus are visible.
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Figure 1. Normal canine esophagus and lower esophageal sphincter.

Esophageal Abnormalities

Megaesophagus. Megaesophagus is typically a radiographic diagnosis, but esophagoscopy can be employed to rule out obstructive causes of dilatation and/or identify evidence of primary or secondary esophagitis.

Typical appearance is a markedly dilated, flaccid, and cavernous lumen from the cervical esophageal sphincter (CES) to the lower esophageal sphincter (LES). Often variable amounts of froth, fluid, and ingesta are present.

Esophagitis. Esophagitis can be triggered by a variety of underlying processes, including gastric reflux, foreign body presence, irritant chemicals or medications (eg, doxycycline, clindamycin), and infections (eg, CandidaSpirocerca).

Gross mucosal findings tend to be variable depending on underlying cause and severity. Changes supportive of esophagitis include hyperemia, friability, granularity, erosions, ulcerations, necrosis, or presence of a pseudomembrane. In addition, the LES may be open, with fluid pooling in the distal esophagus (Figure 2).

Stricture. Stricture can be diagnosed using contrast radiography but is best characterized and treated with esophagoscopy. Strictures are often encountered in the intrathoracic esophagus near the heart base, and the degree of luminal narrowing and length of the stricture vary. Uncommonly, patients may have more than one stricture.

Most strictures appear as a focal, circumferential narrowing formed by a smooth, white fibrous ring. Most important, the lumen in this area does not distend with constant insufflation. Orad to the stricture, a variable degree of dilatation, depending on the chronicity of the lesion, is present. Thoroughly inspect the mucosa in the area for evidence of associated esophagitis (Figure 3).

Esophageal Neoplasia. Depending on tumor type and size, appearance of intraluminal lesions vary but can include proliferative, lobulated, or smooth masses that may be friable or have areas of ulceration on their surfaces. The presence of the mass inevitably creates some degree of luminal obstruction and, therefore, may lead to orad dilation of the esophagus.

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Figure 2. Abnormal canine esophagus with an open LES and pinpoint mucosal hemorrhages consistent with esophagitis.


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Figure 3. Canine esophageal stricture.


Gastroscopy is indicated:

  • In acute cases, when a gastric foreign body or severe gastric ulceration is suspected
  • As part of a complete UGIE in patients with chronic GI signs
  • For therapeutic procedures, such as foreign body retrieval, feeding tube placement, polypectomy, and to achieve hemostasis of a bleeding ulcer.

Initial Evaluation

Clinical Signs. Gastroscopy can be used to investigate and treat both acute and chronic GI signs, including vomiting/hematemesis, poor appetite, hypersalivation, melena, and weight loss.

Diagnostics. Appropriate diagnostic evaluation prior to a UGIE—which applies to gastroscopy and enteroscopy—includes:

  • Routine bloodwork
  • Fecal testing
  • Screening for Addison’s disease
  • Preliminary imaging (abdominal radiographs or ultrasound).

If possible, patients should undergo a conservative therapeutic trial using a hypoallergenic food to exclude dietary allergy. This is particularly important because histopathology cannot readily distinguish between patients with food allergies and those with inflammatory bowel disease (IBD) that require immunosuppression.

Normal Appearance

When evaluating the stomach, it is important to note that rugal folds will take on a markedly different appearance—and color—depending on degree of insufflation. As the stomach becomes overdistended, the mucosa may look blanched or white.

Gastric Abnormalities

Gastritis. With mild gastric inflammation it is important to note that the gastric mucosa may appear grossly normal. More significant inflammation manifests as mucosal thickening, increased granularity, friability, and erosions (Figure 4).

Ulcerative DiseaseErosions are shallow mucosal disruptions that are typically red to brown/black in color. Hemorrhage appears as discrete petechiae and/or red streaks without associated mucosal breaks.

Ulcers represent deep mucosal disruption extending into the submucosa. They often have a central lesion with either a dark brown/black color representing dried blood or yellow/white center representing necrosis. The surrounding border is typically elevated and thickened, creating a crater-like appearance. Ulcers are commonly found in the antrum and pylorus (Figure 5).

Polyp. A polyp is a sessile or pedunculated protuberance of the gastric mucosa most often found in the antrum and pylorus. If small and nonobstructive, a polyp may represent an incidental finding; however, they may be partially obstructive or have surface bleeding/ulceration.

Neoplasia. Gastric neoplasia can take on varied appearances, ranging from a discrete mass (Figure 6) to diffuse infiltrative changes, which can include loss of rugal fold architecture, plaque-like lesions, or general thickening.

Adenocarcinoma is the most common gastric neoplasm in dogs, commonly associated with ulceration and often identified in the antrum or lesser curvature. Lymphosarcoma is the most common neoplasm in feline patients.

Abnormal Motility. As with esophagoscopy, motility disorders are typically diagnosed prior to endoscopy via clinical history and radiographic studies. However, endoscopic imaging and biopsies can identify an etiology for the abnormal motility. Findings that suggest a motility problem include presence of fluid (especially bile stained fluid), food retention (following an appropriate fast), and increased erythema.

Figure 4. Normal feline rugal folds (A). Abnormal canine rugal folds; note the swollen, glassy appearance. Histopathology was consistent with gastritis (B).

Figure 4A

Figure 4-A

Figure 4B

Figure 4-B

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Figure 5. Canine gastric ulceration.

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Figure 6. Discrete mass located in the gastric antrum; histopathology was consistent with an adenoma.



Enteroscopy or duodenoscopy is performed as part of the diagnostic evaluation of patients with chronic GI disease. It is the final portion of the proximal GI tract to be evaluated as part of a UGIE. Clinical indications are similar to those of gastroscopy, with the addition of diarrhea.

Normal Appearance

The mucosa varies from pink/red to yellow/white. In general, dogs tend to have more vibrant coloration compared to the pale pink/creamy color of feline mucosa. The duodenal mucosa is textured with a rough, grainy, or even shaggy appearance (texture represents villi) (Figure 7). In the dog, Peyer’s patches, which appear as discrete, white, circular indentations or craters, may be present (Figure 8).

If possible, the duodenal papillae should be identified. Located in the proximal duodenum of the dog are two papillae (major and minor) that appear as small circular buttons that may be flat or raised. Cats have only the major duodenal papilla, which can be challenging to identify (Figure 9).

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Figure 7. Normal duodenal mucosa and duodenal papilla of the dog.

Figure 8

Figure 8. Peyer’s patches in the lateral wall of the canine duodenum.

Figure 9

Figure 9. Normal feline duodenal papilla.

Duodenal Abnormalities

Inflammatory Bowel Disease. Inflammation can take on a variety of appearances, ranging from normal to severe changes in coloration (erythema) and/or mucosal texture (nodular, increased granularity, proliferation) (Figure 10). Inflamed tissue tends to be more friable, and bleeding may be noted.

Lymphangiectatic Villi. Lymphangiectatic villi are swollen, which manifests as increased mucosal texture, and the mucosal color tends to be more creamy white and glistening in appearance. Varying degrees of inflammation often accompany lymphangiectasia; therefore, the mucosal appearance may be very similar to that of IBD, and biopsies are necessary to distinguish between the two diseases.

Focal Neoplasia. Focal neoplastic lesions are often characterized by mucosal irregularity and ulceration, and may result in narrowing of the lumen, creating a partial to complete obstruction. Diffusely infiltrative cancer can significantly increase granularity or manifest as plaque-like lesions. While lymphoma and adenocarcinoma are the most common neoplasms identified in the small intestine, mast cell tumors, leiomyoma/leiomyosarcomas, and fibrosarcomas may also occur.

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Figure 10. Abnormal canine duodenum with increased granularity; histopathology confirmed inflammatory infiltrate consistent with IBD.


UGIE is a minimally invasive technique that can provide diagnostic information in the evaluation of patients with chronic GI disease. In addition, esophagoscopy and gastroscopy can be employed for diagnostic and therapeutic purposes in patients with acute GI diseases.

Part 2 of this article will outline appropriate UGIE techniques, and a future article will specifically focus on endoscopic evaluation and removal of upper GI foreign bodies.

CES = cervical esophageal sphincter; GI = gastrointestinal; IBD = inflammatory bowel disease; LES = lower esophageal sphincter; UGIE = upper gastrointestinal endoscopy

Suggested Reading

  • Matz ME, Twedt DC. Endoscopic procedures for evaluation of the gastrointestinal tract. In Ettinger SJ, Feldman EC (eds): Textbook of Veterinary Internal Medicine, 7th ed. St. Louis: Saunders, 2010, pp 443-446.

F01_AJulie Callahan Clark, DVM, Diplomate ACVIM, is a lecturer in small animal internal medicine at University of Pennsylvania School of Veterinary Medicine. She received her DVM degree from Tufts University, and completed an internship at New England Animal Medical Center in West Bridgewater, Massachusetts and a residency in internal medicine at University of Pennsylvania.