Figure 4-74 Superficial gastric erosions with hemorrhage along the greater curvature of the stomach in a 3-year-old Boxer with intermittent vomiting, chronic diarrhea, anorexia, and weight loss. Gastric biopsy specimens showed histologic evidence of mild erosive subacute gastritis. Histiocytic ulcerative colitis was also identified.

Figure 4-75 Erosions in the distal antrum of two dogs that were receiving both prednisone and flunixin meglumine in an experimental study. A, Day 4 of combination drug administration. B, Multiple erosions at day 2 in a dog receiving prednisone at 1.1 mg/kg (0.5 mg/lb) once daily and flunixin meglumine at 1.1 mg/kg (0.5 mg/lb) twice daily. It is recommended that nonsteroidal anti-inflammatory drugs not be used in combination or in conjunction with corticosteroids because of the risk of gastric ulceration.

(Courtesy of Steven W. Dow.)

Figure 4-76 Large ulcer with a shallow crater in the gastric body of a cat (6-o’clock position). Note the normal appearance of the surrounding mucosa.

Figure 4-77 Shallow ulcer in the proximal antrum of a cat (arrow). A small amount of hemorrhage is associated with the ulcer. An open pylorus is seen at the far end of the field.

Figure 4-78 Large antral ulcer in a 14-year-old Cocker Spaniel. Methylprednisolone acetate had been administered for severe degenerative joint disease, and the dog’s owner instituted ibuprofen without notifying the clinician. A, Antral canal from the distal gastric body. A large ulcer is seen in the right aspect of the field of view (3-o’clock to 4-o’clock position), and the pylorus is in the center of the field. The tissue projection on the antral wall at the 6-o’clock position is a polyp (an incidental finding and insignificant lesion). B, Close-up view of the gastric ulcer. Much of the ulcer pit is filled with hemorrhages. The antral canal is to the left. On initial approach this ulcer was poorly visualized because it was covered by thick foam, mucus, and bile. Once the fluid and mucus were suctioned away, the ulcer was clearly seen.

Figure 4-79 Large angulus ulcer in a 12-year-old Chow with severe degenerative joint disease. Aspirin and corticosteroids were administered simultaneously. A, Ulcer in the angulus. Biopsy samples were obtained from the upper wall (shown here) and the rim. No evidence of neoplasia was found. Treatment included famotidine and sucralfate. B, Early signs of healing at 14-day follow-up. Large ulcers may take 8 to 16 weeks to heal.

Figure 4-80 Perforated gastric ulcer in an 8-year-old Chow that had received naproxen (a nonsteroidal antiinflammatory) once daily for 7 days. On the sixth day, vomiting and inappetence were first noted by the owner. Naproxen was discontinued after the seventh day, but the clinical signs persisted. Famotidine and misoprostol were started 3 days later. The vomiting soon subsided, but inappetence persisted. Nine days after naproxen was discontinued, the dog was presented for endoscopy. The dog was bright and alert. The complete blood count and biochemical profile were completely normal except for mild leukocytosis. The packed cell volume was 48%. A, View toward the antrum from the lower gastric body. Two ulcers are seen: a smaller lesion at the 9-o’clock position and a much larger ulcer to the right of center (midantrum). B, On advancement into the antrum the endoscope revealed a very deep ulcer with a thick rim (entire upper left quadrant). C, Straight-forward view into the ulcer. The whitish meshlike tissue seen through the ulcer crater is omentum. The pyloric orifice is at the lower left (7-o’clock position). D, Close-up view of the ulcer crater with an omental seal.

E, To determine whether the omental seal was incomplete and whether surgery needed to be performed immediately rather than on the following day (the endoscopy was being conducted late in the day), survey abdominal radiographs were obtained to look for evidence of free air in the abdominal cavity (air was insufflated to the stomach as for routine gastroscopy). The radiograph shows no evidence of free air in the abdominal cavity. Barium was present in the colon from a contrast series started by another veterinarian a few days before. Barium transit was thought to be delayed by anticholinergic therapy that had been started several days earlier in an effort to control vomiting. (Anticholinergic treatment is not advisable.) F, For comparison, a survey abdominal radiograph from a different patient with a perforated gastric ulcer shows free air in the abdominal cavity between the liver and stomach. Note: The Chow underwent surgery the following day, and the ulcer was found to have a firmly adhered, complete omental seal. A partial antrectomy was done, and the histologic diagnosis was focal chronic ulcerative gastritis. (Ulcer tissue should always be sampled to rule out neoplasia.) An incidental finding at surgery was a mass in the left medial lobe of the liver. The lobe was resected, and the mass was determined to be a hepatocellular carcinoma. The dog was fed via jejunostomy tube for 12 days and had an uneventful recovery. The Chow lived for 3 years after surgery with no evidence of tumor recurrence.

Figure 4-81 Two peripyloric ulcers in a 14-year-old dog that was receiving nonsteroidal antiinflammatory drug (NSAID) therapy for severe osteoarthritis. The pyloric orifice (center) is open, and ulcers are seen to the left and above the pylorus (with hemorrhage). In animals that are sensitive to NSAIDs the prostaglandin drug misoprostol has proved very effective in preventing gastrointestinal ulceration.

Figure 4-82 Gastric fluid and bile retention in a 7-year-old Pekingese with an idiopathic gastric motility disorder. Note the mucosal erythema. Mucosal biopsy specimen results were normal. Clinical signs included intermittent vomiting, frequent nausea and loud gastric gurgling sounds, periodic inappetence, and occasional bloating episodes.

Figure 4-83 Grass blades and food in the gastric body of a 3-year-old Doberman with lymphangiectasia. The dog was quite weak and had a total protein concentration of 2.3 g/dL. The dog had not eaten or been outdoors in 3 days. Gastric mucosal biopsy specimen results were normal.

Figure 4-84 Large amount of retained food (canned) in a 6-year-old Cocker Spaniel with a disorder characterized by the vomiting of undigested or partially digested food 18 to 24 hours after eating. At the time of endoscopy the dog had not eaten in 30 hours. The endoscope was maneuvered beyond the food, and the pylorus was traversed without difficulty. A thyroid-stimulating hormone test was consistent with hypothyroidism. Gastric and duodenal biopsy specimen results were normal. The animal responded well to thyroid supplementation and metoclopramide.

Figure 4-85 Food and fluid retention in the gastric body of a 10-year-old miniature poodle. The surrounding mucosa appears normal.

Figure 4-86 Retroversion view of the proximal stomach of a 1-year-old Kuvasz with a 6-month history of intermittent vomiting. Note the presence of bile-stained fluid. No metabolic abnormalities were found, and gastric and duodenal biopsy results were normal. An idiopathic gastric motility disorder was diagnosed, and the animal responded well to metoclopramide.

Figure 4-87 A, Gastric fluid retention in a 2-year-old Balinese with anorexia (5 days) and vomiting. Several of the vomiting episodes were projectile in nature. B, Retroversion view of the fundus and gastroesophageal junction. Most of the gastric fluid was suctioned so that a thorough examination could be completed. No evidence of a foreign body was found. C, The pylorus was unusually dilated in this cat. The duodenal wall can be seen at the far end of the canal. Duodenal biopsies revealed chronic active enteritis. Esophagitis was most likely secondary to vomiting. The result of a barium series done after endoscopy to rule out a lower small bowel obstruction was normal. The increased gastric fluid was most likely secondary to marked duodenal–gastric reflux and abnormal gastric motility. Treatment included metoclopramide and prednisone.

Figure 4-88 Pronounced antral folds in a 16-year-old dog with chronic diarrhea and a ravenous appetite. The animal had no clinical signs that were specific for gastric disease. Biopsies showed antral fibrosis, which was probably the sequela of a previous inflammatory disorder. A, Endoscopic view from the proximal end of the insufflated antrum. B, Distal antrum with smooth folds. The pylorus is near the top in the field of view at the 12-o’clock position.

Figure 4-89 Pronounced folds in the distal antrum of a 10-year-old Beagle with intermittent vomiting. This dog had mild hypertrophic gastropathy. The pyloric orifice is obscured by foam to the left of center (10-o’clock position).

Figure 4-90 Pronounced folds around the pylorus of a 14-year-old cat with intestinal and hepatic lymphoma. The closed pylorus is to the left of center at the 9-o’clock position. Biopsy samples obtained from the thickened tissue around the pylorus showed no histologic evidence of neoplasia. (This was confirmed at necropsy.) The diagnosis was proliferative gastropathy with mild inflammation.

Figure 4-91 Hypertrophic gastritis in a 10-year-old poodle with a 3-month history of intermittent vomiting. Survey abdominal radiographs showed marked gastric distension with fluid and gas, and a barium series revealed marked delay in the emptying of barium from the stomach. At endoscopic examination the pyloric orifice was extremely narrow (slitlike area in center of field), and it did not open to any degree during the examination. The tissue around the pylorus tended to bulge up (as shown here) any time gastric contractions occurred. A Y-U pyloroplasty was performed, and hypertrophic gastritis was diagnosed based on the results of full-thickness biopsy.

(Courtesy of Susan E. Johnson.)

Figure 4-92 Large, benign polyp in the midgastric body of a 12-year-old Chow. This is an unusual location. The polyp was not clinically significant. A, Forward view from the proximal gastric body. B, Close-up view of the polyp.

Figure 4-93 Two small antral polyps, an incidental finding in a 16-year-old dog.

Figure 4-94 A, Barium contrast radiograph of a 6-year-old domestic short hair cat with a history of lifelong intermittent vomiting. For some time before this presentation the cat had been vomiting daily, with some episodes being projectile in nature. The pyloric antrum has a filling defect (a consistent finding throughout the series). B, A large polyp with irregular surface was identified in the distal antrum. In this view the polyp occludes the pyloric orifice. The antral mucosa also displayed erythema and irregularity. C, Biopsy forceps were used to move the polyp to the side, providing a partial view of the pyloric orifice. The polyp was freely movable on a stalk. D, Polyp biopsy procedure. The polyp had a soft surface. Note the irregularity of the antral walls. The histologic diagnosis was benign inflammatory polyp. Chronic gastritis and moderate lymphocytic enteritis were also present.

Figure 4-95 Gastric polyp in a 7-year-old Great Dane with intermittent vomiting, diarrhea, and occasional hematochezia. A, View of the antrum from the lower gastric body. The angulus fold extends right to left at the top of the field. A soft, movable mass is present in the antrum near the pylorus. B, Close-up view of the mass. C, The endoscope was passed beyond the mass to the pylorus, which was open and readily traversed. Note: Endoscopic biopsies were consistent with a diagnosis of benign gastric polyp. Colonoscopy revealed a mass (adenocarcinoma) in the mid-descending colon. The gastric mass was subsequently resected because the vomiting was thought to be due, in part, to the size and location of the lesion. Surgical biopsies confirmed the diagnosis of benign gastric polyp.

Figure 4-96 Pyloric polyp in a 7-year-old Pug with frequent vomiting. Some episodes were projectile in nature. A, The polyp caused distortion of the pyloric orifice and occlusion of the pyloric canal. In this photograph the pyloric orifice appears as an inverted V with the polyp protruding through it. B, The biopsy forceps have been passed through the pyloric canal. Note that the polyp has compromised the lumen. This is an unusual location for a polyp. C, Surgically excised tissue from the pylorus.

Figure 4-97 Initial endoscopic series in a 10-year-old cat with vomiting, weight loss, and inappetence. A, Immediate view on entering the stomach. A small amount of air has been insufflated. A large mass is seen at the lower aspect of the field of view. The angulus is at the 12-o’clock to 1-o’clock position. B, The edge of the mass is at the 7-o’clock to 8-o’clock position. Note the irregularity and thickening of the rugal folds around the mass in both views. C, Close-up view of the large mass in the proximal stomach. D, View of the mass and surrounding irregular folds after the retroversion maneuver. The cat lived for 8 years after the diagnosis was made.

E, A significant amount of bleeding occurred after a single biopsy sample was obtained from the center of the mass. F, Samples were obtained from the mass and surrounding tissue. The mass was sampled several times in the same location in an effort to obtain tissue as deeply as possible. G, The mass is in the upper left aspect, and hemorrhage from a mucosal-fold biopsy site is seen in the center of the field.

Figure 4-98 Endoscopic examination of the cat shown in Figure 4-97, done 19 days after the initial examination. Treatment involved only chemotherapy (prednisone, cyclophosphamide, and vincristine). A, Forward view of the proximal stomach at slightly more than moderate distension. The mass, which had decreased dramatically in size, is in the center of the field. (Compare with Figure 4-97, C.) B, Retroversion view. The site of the mass is barely detectable (focal reddened area to left of center). (Compare with Figure 4-97, D.) C, Retroversion view at a different angle. The mass can be seen at the 7-o’clock position.

Figure 4-99 Endoscopic photographs of the cat discussed in Figures 4-97 and 4-98, obtained 19 weeks after the initial examination. The patient was doing extremely well while undergoing chemotherapy. No evidence of a gastric mass is seen, and the mucosa at the original site of the lesion appears whiter than the surrounding mucosa. A, Forward view of the proximal stomach in mild distension. Note that the rugal folds no longer appear thickened or irregular. B, Same site as in A but with moderate distension. C, Close-up view of the gastric mucosa. Note the smooth mucosal surface.

Figure 4-100 Endoscopic photographs of the cat in Figures 4-97, 4-98, and 4-99, taken 9 months after the animal was first examined. A, Forward view of the proximal stomach in mild distension. B, Forward view of the stomach in moderate distension. The stomach is grossly normal except for the small, whitened area where the mass was previously located (compare with Figures 4-97, C; 4-98, A; and 4-99, A). Biopsy samples showed no evidence of lymphosarcoma. The cat was still receiving chemotherapy and was clinically normal. Chemotherapy was discontinued at 12 months; at 18 months, no evidence of tumor recurrence was found. Note: The cat lived 8 years after the diagnosis was made. Chemotherapy never had to be resumed. This case highlights the importance of using endoscopy relatively early in animals with unexplained chronic vomiting. This cat’s history was easily consistent with a diagnosis of inflammatory bowel disease or chronic gastritis, yet endoscopy revealed lymphosarcoma. Early initiation of the most indicated therapy resulted in an excellent outcome. (Also see Figure 4-110 for illustration of an additional incident involving this patient: gastric hairball.)

Figure 4-101 Lymphosarcoma involving the gastric body and fundus in a 12-year-old Siamese cat. A readily palpable mass was found in the anterior abdomen (stomach). Lymphosarcoma was also identified in the colon. A, Forward view in the gastric body. The stomach has not been insufflated. Note the dramatic distortion of the normal rugal fold structure and the ulcerative change at the 5-o’clock position. B, Retroversion view showing the multiple mass effect in the proximal stomach and fundus. C, Forward view in the gastric body. Note the irregular rugal fold adjacent to the mass. The animal responded fairly well to chemotherapy for 6 weeks, but then clinical signs worsened and the cat was euthanized. D, Distal gastric body. A short edge of the angulus is seen at the far lower right (5-o’clock position). The proliferative effect from the lymphosarcoma stopped abruptly in the lower body. The antrum was completely normal.

Figure 4-102 Antral lymphosarcoma in a 14-year-old cat with a short history of inappetence and occasional hematemesis. A, The gastric body was completely normal. B, The antrum was infiltrated with proliferative tissue. Failure to examine the antrum would have resulted in a missed diagnosis. The histologic diagnoses were normal gastric body, antral lymphosarcoma, and moderate lymphocytic, plasmacytic enteritis. The cat did well on chemotherapy for 5 months, but then bilateral renomegaly developed quite rapidly. The cat was subsequently euthanized because of anorexia and vomiting. The blood urea nitrogen and creatinine levels were normal. Histologic examination of tissues obtained at necropsy identified lymphoma in both kidneys and the antrum.

Figure 4-103 Gastric lymphosarcoma in an 8-year-old cat with inappetence. The animal had tested positive for the feline leukemia virus. A physical examination revealed a palpable abdominal mass. A and B, Lateral and ventrodorsal radiographs showed a soft tissue mass involving the stomach. Gastroscopic examination showed a single mass along the distal lesser curvature and several prominent linear masses in the antrum. C, Retroversion view showing the normal fundus and gastroesophageal junction. D and E, Mass effect in the antral canal has caused marked occlusion. At the top of the field of view, note the cavernous area with debris. The pylorus is not in view. The endoscope was advanced to the pylorus through the tunnel seen at the bottom of the photographs.

Figure 4-104 Examination of the cat shown in Figure 4-103, performed 5 weeks after presentation. Chemotherapy dramatically decreased the size of the antral masses. The endoscope is in the same position as in Figure 4-103, D-E. The pylorus is closed, but its orifice is seen in the center of the field. One of the antral masses, although somewhat smaller, is still evident in the left aspect of the field. The debris-filled cavern is no longer present.

Figure 4-105 Gastric adenocarcinoma in a 14-year-old Siamese cat with a 2-week history of anorexia but only occasional vomiting. A and B, Barium contrast radiographs showed incomplete gastric filling and mucosal irregularity. C, Immediate view when the endoscope entered the stomach. Note the thickened, irregular rugal folds. The walls of the stomach were poorly distensible in response to air insufflation. D, Mucosal irregularity and focal hemorrhages along the distal greater curvature. E, White plaque material (left of center) adhering to the mucosa of the greater curvature. F, Prominent folds in the antral canal. The pylorus is to the left of center at the 11-o’clock position. Multiple biopsy samples were obtained from the gastric-body lesions. The tissue felt unusually hard when the biopsy forceps were closed. This tactile perception is often associated with malignancy.

Figure 4-106 Gastric adenocarcinoma in a 9-year-old male Bouvier with a 5-month history of intermittent vomiting (one or two episodes per week and no worrisome associated signs). The complete blood cell count, biochemical profile, serum thyroxine concentration, urinalysis, fecal examination for parasites, and survey radiographs of the thorax and abdomen were unremarkable. The dog was referred for endoscopy because the owner was anxious to determine why the animal was vomiting. A, View from the proximal antrum. The antral walls are smooth and normal. However, a proliferative mass was found in the pylorus. B, Close-up view of the pyloric mass, which is occluding most of the pyloric orifice. C, View of the pyloric canal near the pyloroduodenal junction after the endoscope was advanced into the pyloric canal, beneath the mass. The mass extended into the proximal duodenum. The histologic diagnosis was adenocarcinoma. D, Grossly normal duodenum in the area of the major duodenal papilla (upper center). This very important finding indicates that resection would not need to extend very far down the descending duodenum. The duct area appeared unaffected. Note: A 30-cm section of antrum, pylorus, and duodenum was resected during a 4-hour surgical procedure. No evidence of metastasis was found, and the adenocarcinoma did not involve the deep layers of the pylorus. The dog’s recovery was uneventful. Long-term metoclopramide therapy was prescribed to help decrease duodenogastric reflux because the animal no longer had a pylorus. The dog lived 3 years after surgery, with no evidence of tumor recurrence. E, Endoscopic view of the antral–duodenal junction (site of the anastomosis) 8 months after the dog was first examined. The anastomosis site between the proximal gastric antrum and the duodenum is in the field of view. (Note the ridged area extending from the 5-o’clock to 12-o’clock position). Results of biopsy specimens obtained from the area were normal (as they were at 12 and 24 months after surgery).

(From Tams TR: Gastrointestinal symptoms. In Tams TR, editor: Handbook of small animal gastroenterology, Philadelphia, 1996, Saunders).

Figure 4-107 Gastric adenocarcinoma. A, Marked proliferative changes in the lower gastric body, with complete loss of the normal rugal fold architecture. B, Lower gastric body with an area of superficial ulceration seen in the lower field. C, Close-up view of a mass in the midgastric body. The mass was rigid and had a very dense wall (suggestive of neoplasia). Masses such as this one should be sampled as deeply as possible. If only superficial tissue is obtained, the endoscopist may fail to retrieve neoplastic cells. The first four attempts to biopsy the mass yielded very small tissue samples, but on the fifth attempt the biopsy instrument advanced inside the mass (the view in this photo). A number of large tissue samples were obtained, and the diagnosis of adenocarcinoma was confirmed. Biopsy specimens were also obtained from the ulcerated area shown in B.

Figure 4-108 Secondary changes (thickening) of the rugal folds in a 12-year-old mixed-breed dog with Zollinger-Ellison syndrome. In this syndrome, gastrin is released into the circulation by a gastrinoma (a tumor usually located in the pancreas). The release of gastrin leads to expansion of the parietal cell mass with an enhanced capacity to secrete gastric acid. The rugal folds thicken because of the trophic effect of gastrin. This dog also had hyperemia of the distal esophagus. Between 90% and 95% of humans with Zollinger-Ellison syndrome have upper gastrointestinal ulceration at some time during the course of their disease. No ulceration was identified in this dog. A gastrinoma was found in the pancreas at surgery.

(Courtesy of Robert G. Sherding.)

Figure 4-109 Small accumulation of hair in the distal gastric body and proximal antrum of a cat with chronic intermittent vomiting. The angulus is at the lower right aspect of the field. Gastric biopsy results were normal, and duodenal biopsy results revealed inflammatory bowel disease. The hair was thought to be an incidental finding.

Figure 4-110 A, A large tubular hairball extends slightly into the distal gastric body from the antrum. The angulus is in the right aspect of the field. B, The hairball has been grasped with a two-prong foreign body grasper and is being pulled into the gastric body. C, The retrieved hairball. Note: These photographs are of the cat with gastric lymphosarcoma that was discussed in Figures 4-97 through 4-100. The owner reported recurrence of intermittent vomiting 19 weeks after the animal began receiving chemotherapy. Based on gastroscopy (no evidence of any mass recurrence) and the cessation of vomiting after the hairball removal, the vomiting was caused by the hairball and not loss of remission from lymphosarcoma.

Figure 4-111 Physaloptera parasite on the gastric mucosa of a dog (center of field). The white image at the right (3-o’clock position) is due to light reflection. See also Figure 8-18 for another example of Physaloptera parasites observed at gastroscopy.

(Courtesy of Michael S. Leib.)

Chapter 4 Gastroscopy

Todd R. Tams

Gastroscopy mainly identifies abnormalities of the gastric mucosa, but it may also reveal distortion of the stomach’s normal anatomic relationships by displacement or extrinsic compression as a result of a mass or enlargement of an adjacent organ. Gastroscopy has become the most valuable diagnostic method available for evaluating primary gastric disorders because it permits unparalleled observation of the gastric mucosa. This modality significantly increases the diagnostic yield in comparison with contrast radiographic studies, which are somewhat less sensitive in the evaluation of mucosal disorders. The diagnostic yield in animals with neoplasia that is in the deeper layers of the stomach or in the pyloric wall but that is not visible in the mucosa is significantly enhanced when both ultrasound and endoscopic examinations are performed. Endoscopy-guided biopsy provides rapid and reliable assessment of many disorders. Endoscopic examination of the stomach has improved early diagnostic capability significantly and has highlighted the fact that gastric mucosal disorders occur fairly often.

Indications

Indications for gastroscopy include clinical signs referable to gastric diseases, including nausea, salivation, vomiting, hematemesis, melena, unexplained abnormal breath changes, and anorexia. The most common disorders diagnosed include chronic gastritis (with or without overgrowth of Helicobacter organisms), superficial gastric erosions, gastric foreign bodies, and gastric motility disorders. Ulcers and neoplasia can be readily diagnosed but are somewhat less commonly found. The antral–pyloric canal can be examined, and significant narrowing of the pylorus or the presence of prominent folds of tissue in the antrum may suggest the possibility of hypertrophic gastropathy.

Vomiting is one of the most common reasons animals are presented to veterinarians for examination. In many cases a history of dietary indiscretion (e.g., overeating or an acute dietary change) or foreign body ingestion can be elicited. Gastroscopy is not commonly performed in patients with acute vomiting unless a gastric foreign body or gastric ulceration is suspected. This examination is much more commonly done in animals with a history of acute vomiting that has continued for a period of time without relief (i.e., greater than 3 to 4 days), chronic intermittent vomiting (i.e., recurrent for more than 2 to 3 weeks), and vomiting that includes blood. (Gastroscopy should be considered any time hematemesis is observed.) The most common causes of hematemesis in dogs and cats are chronic gastritis and acute gastric mucosal erosions from factors such as drugs (especially nonsteroidal antiinflammatory medications) and hypotension with subsequent decreased gastric mucosal blood flow. Gastric ulcers and neoplasia are somewhat less common causes of hematemesis. Occasionally the only clinical manifestations of chronic gastritis are inappetence and salivation.

An initial diagnostic plan for an animal with a chronic vomiting disorder should include a complete history, physical examination, complete blood count, complete biochemical profile (including thyroid evaluation for vomiting cats), urinalysis, fecal examination for parasites (both centrifugal flotation and a Giardia antigen test), evaluation for heartworm disease in cats (starting with a heartworm antibody test), and survey abdominal radiographs. Once disorders such as metabolic abnormalities (e.g., renal failure, diabetes mellitus, and liver disease), a foreign body that can be readily diagnosed on survey abdominal radiography, and dietary indiscretion or food sensitivity are ruled out, the decision to perform more in-depth diagnostic tests is made. This may include testing for disorders that may not be identified on baseline screening tests (e.g., consider the possibility of pancreatitis not diagnosed in the acute phase, leptospirosis, and atypical hypoadrenocorticism), barium contrast study, ultrasonography, or upper gastrointestinal (GI) endoscopy (or a combination of ultrasonography and gastroscopy). Clinical acumen is important in deciding which tests make the most sense, based on patient presentation and recent history and physical examination findings. Given the insensitivity of barium contrast studies for diagnosing mucosal disorders, the thoroughness of a complete gastric endoscopic examination combined with the ability to examine the upper small intestine at the same time, and the cost-containment factor that concerns many pet owners, the decision to choose gastroscopy over contrast radiography is usually a sound one. Ultrasonography is especially useful for evaluating wall thickness. The conclusion that endoscopy is an excellent way to examine for gastric disease should come as no surprise to the increasing number of small animal practitioners who are performing endoscopy. If radiographs identify a lesion or foreign body, gastroscopy or surgery is still necessary for definitive diagnosis and treatment. Furthermore, a normal gastric contrast radiographic examination does not rule out the presence of a gastric disorder.

In patients with chronic upper GI disorders, gastroscopy should be performed in conjunction with esophagoscopy and duodenoscopy. Important diagnostic clues may be evident in any or all of these areas during the course of an examination. Follow-up gastroscopy is a valuable aid for monitoring the therapeutic response in patients with chronic gastritis or ulcers. Follow-up examination and biopsies are especially important in animals with chronic, severe histiocytic and granulomatous gastritis, chronic fibrosing gastritis, and gastric lymphosarcoma. Important information that is useful in treatment protocol decisions can often be obtained. (Case examples highlighting this point can be found in the “Atlas” section at the end of this chapter.)

Finally, esophagogastroduodenoscopy (EGD) is a most useful aid when clients have limited financial means but earnestly wish more than palliative treatment for their pet’s discomfort. If inexpensive routine tests have proved unrewarding in diagnosing a disorder characterized by GI signs, money may be better spent on early endoscopic examination.

Instrumentation

For small animal patients a complete evaluation of the stomach is best accomplished with the use of a flexible endoscope with a diameter of 9.8 mm or less and four-way tip deflection capability (see Chapter 2). In cats and in dogs weighing less than 5 kg (11 lb) an endoscope insertion-tube diameter of 9 mm or less is highly preferred (smaller 7.8-mm scopes are ideal). The use of a smaller endoscope makes it much more likely that the pyloric canal and proximal duodenum can be traversed and examined in these small patients than when a larger diameter scope is used, especially if the operator has limited experience.

Patient Preparation

The main requirement for a successful gastroscopy is that the patient’s stomach be empty. No food should be given for 12 to 18 hours before the examination, and water should be withheld for 3 to 4 hours.

Under certain circumstances, fasting alone is insufficient to ensure an empty stomach. If gastric emptying is significantly impaired because of abnormal gastric motility (e.g., idiopathic gastric hypomotility or severe chronic gastritis) or obstruction (e.g., hypertrophic gastropathy or antral or pyloric neoplasia), significant amounts of ingesta, debris, or retained gastric or duodenal fluid may compromise the examination. In these situations, biopsy specimens may still be obtained if areas of mucosa can be visualized, but because lesions can be easily missed, the examination may need to be repeated later. Finding retained ingesta in a properly fasted animal can be an important diagnostic clue. For example, the presence of retained ingesta may strongly suggest that the patient has a gastric motility disorder.

When clots or pooled blood is present, the endoscopist may find it difficult to determine the source of bleeding. Free fluid can be suctioned through the accessory channel, but copious lavage through a large-bore tube may be necessary to dislodge clots before the endoscope is reintroduced.

Gastroscopy is generally not performed within 12 to 24 hours of a barium contrast examination unless a gastric foreign body has been identified. This usually allows sufficient time for complete clearing of the barium and subsequent thorough mucosal evaluation. The accessory channel of an endoscope should not be used to suction undiluted barium because residue may adhere to the channel wall.

Anesthesia and Positioning

As with any endoscopic procedure of the upper GI tract, general anesthesia is required for gastroscopy. Anesthetic agents can affect intestinal motility and sphincter function (including the lower esophageal sphincter and the pylorus), and consideration should be given to selecting anesthetic agents that will minimally hinder the endoscopist’s ability to advance the endoscope through the stomach and pylorus. Atropine and other anticholinergic agents are not used unless they are required to increase heart rate. These drugs alter gastric motility patterns, which may cause increased gastric flaccidity and dilation. In addition, pyloric tone may increase, making it difficult to advance an endoscope through the pylorus. Atropine can also decrease lower esophageal sphincter tone. In most animals, however, the lower esophageal sphincter is closed on initial examination regardless of whether atropine was administered before the procedure. Pure opioid agonist drugs (e.g., morphine and hydromorphone) should not be used because they may increase pyloric tone. While experienced endoscopists may not have any added difficulty in traversing the pylorus no matter what anesthetic protocol is used, the guidelines listed here work well for a majority of patients undergoing upper GI endoscopy.

Commonly used protocols for upper GI endoscopy include the use of acepromazine and butorphanol for premedication tranquilization/sedation, which will help calm patients before catheter placement and lower the induction and inhalant anesthetic dose requirements, thereby improving cardiovascular performance and easing recovery. Drugs that potentiate vomiting should be avoided in animals with esophageal or gastric foreign bodies (e.g., medetomidine or pure opioid agonists). The patient should be induced with an injectable anesthetic (propofol is most commonly used, but the combination of ketamine/diazepam is also acceptable) and intubated quickly. The endotracheal tube cuff should be appropriately inflated at all times so that inadvertent aspiration of fluid during the procedure is avoided. The cuff should not be deflated until the patient is extubated. Anesthesia is maintained with isoflurane or sevoflurane. Fluid support should be given throughout the procedure as needed (e.g., a balanced, isotonic crystalloid fluid such as Normosol-R or lactated Ringer’s solution administered at 10 mL/kg/hr for patients with normal oncotic pressure and plasma proteins as inhalant anesthetics can cause vasodilation and decreased venous return). Patients that are dehydrated should have their deficits corrected as much as possible before induction of anesthesia. Hypoproteinemic patients may benefit from colloid administration. If there is a need to prevent or control vomiting after the procedure, maropitant (Cerenia) or dolasetron (Anzemet) are highly effective choices.

Minimal monitoring during upper GI endoscopy includes an assessment of heart rate, respirations, and pulse oximetry, and ensuring that the degree of gastric distension does not hinder respirations. Insufflation of the stomach is important for ensuring a complete gastric examination. Prolonged overinsufflation, however, can cause cardiovascular and respiratory compromise. Both the endoscopist and the anesthetist should monitor the degree and effects of insufflation throughout the procedure. If there is too much air in the stomach, it can be easily and quickly decreased with the use of suction through the endoscope. Capnometry, blood pressure, and ECG can be useful for assessing and maintaining normal physiologic variables.

The patient should always be placed in left lateral recumbency for gastroscopy. With the animal in this position the antrum and pylorus are away from the tabletop. This significantly improves the endoscopist’s ability to completely examine and more readily traverse these structures with the scope. When an animal is in right lateral recumbency, it is much more difficult to clearly identify and pass the endoscope around the incisura angularis and through the antrum to the pylorus.

Procedure

All areas of the stomach should be examined completely in every patient that undergoes gastroscopy. Therefore the beginning endoscopist must learn to identify landmarks properly (Figure 4-1). Only after the endoscopist has become familiar with luminal gastric anatomy do maneuvering the endoscope to obtain a retroflexed view of the cardia, advancing the scope around the incisura angularis to reach the antrum, and traversing the pyloric canal become consistent and effortless procedures.

Figure 4-1 Five basic regions of the stomach. The most important landmarks for endoscopy are the cardia, angulus, and pylorus.

Gastroesophageal Junction

Because the esophagus is essentially in a posterior plane compared with the stomach, the endoscope tip needs to be deflected in the distal esophagus before it can be successfully advanced to the stomach. As the endoscope is advanced to the distal esophagus, the position and configuration of the gastroesophageal junction are noted (see Chapter 3). The endoscope tip should be centered at the gastroesophageal orifice. As the scope is advanced, the tip is deflected to the left approximately 30 degrees with simultaneous slight upward deflection as the gastroesophageal junction is passed. In most patients this is easily accomplished by rotation of the outer control knob counterclockwise for left deflection and the inner control knob counterclockwise for upward deflection. In some patients, minimal or no upward deflection is needed. When the endoscope tip is properly directed, no resistance should be encountered as the scope is advanced to the stomach. If the tip is advanced too far before deflection is begun, the endoscope is usually directed into the esophageal wall bordering against the posterior aspect of the lesser curvature of the stomach. If this occurs, the endoscope tip should be retracted and repositioned. Variable degrees of air insufflation of the distal esophagus may be necessary to aid visualization and positioning. In general, air is continually insufflated as the endoscope is advanced along the esophagus and through the gastroesophageal junction (keep fingertip on the air insufflation button).

Proximal Stomach and Gastric Body

The endoscope tip should be positioned just through the gastroesophageal junction so that the endoscopist can become spatially oriented and obtain an overview of the gastric lumen. As the tip enters the stomach, the rugal folds, generally on the greater curvature of the body, are seen. Often the stomach walls are partially or completely collapsed, especially in medium to large dogs or if only a small volume of air was insufflated during esophagoscopy. In this situation the view of the stomach is quite limited, and it is necessary to first pause and insufflate air before attempting to advance the scope. Without sufficient gastric distension, the endoscopist will have difficulty identifying the key landmarks and performing a complete examination of the stomach.

The ideal degree of gastric distension is a matter of judgment. Generally the distension should be at least to the point that the rugal folds begin to separate. This allows for spatial orientation and the identification of most gross abnormalities, such as an ulcer, a mass, or a foreign body. In cats and small dogs the degree of insufflation can be achieved within seconds; in giant breeds, constant insufflation may be necessary for 30 to 120 seconds before adequate distension is achieved. Later in the procedure it may be necessary to distend the stomach to a greater degree so that the entire gastric mucosal surface can be carefully examined (Figure 4-2).

Figure 4-2 Appearance of the stomach at varying degrees of insufflation. A, The endoscope has just been advanced into a collapsed stomach. The gastric walls are closed in around the tip of the endoscope, and it is not possible to examine the stomach. Before attempting to advance farther, the endoscopist should first pause to insufflate air, which will begin to effectively distend the stomach for enhanced visualization. B, With moderate gastric distension the rugal folds are clearly separated, and the mucosa can be thoroughly examined. C, Additional insufflation has caused the rugal folds to become flattened. D, The stomach has been markedly distended with air. Rugal folds are no longer evident, and submucosal vessels are clearly visualized. The endoscope is in a retroversion position, and the cardia and gastroesophageal junction are observed at the top of the field of view (12-o’clock position). Overdistension is unnecessary and should be avoided. Some of the air should be suctioned off at this point as marked overdistension may cause cardiopulmonary compromise. E, Appearance of the gastric body after most of the insufflated air has been suctioned. At the conclusion of any upper gastrointestinal endoscopy procedure, as much air as possible should be removed from the stomach to avoid awaking an animal with a bloated stomach.

Occasionally, the stomach will not readily distend on air insufflation. Causes may include a blocked air/water port (located a the tip of the endoscope; always check before each procedure for patency), rapid reflux of air after it is insufflated to the stomach (assistant should apply digital pressure to the neck area to block air loss from the esophagus), or gastric wall disease that limits its ability to stretch and distend (uncommon occurrence).

On the other hand, during insufflation the endoscopist must be careful not to overdistend the stomach because this may result in significant cardiopulmonary compromise. When the stomach is overdistended, the rugal folds become almost completely flattened or undetectable, superficial blood vessels can sometimes be observed, and the mucosa may appear blanched (see Figure 4-2). The respiratory rate may increase significantly. The endoscopy assistant should be constantly aware of changes in the character of the patient’s respirations and any increase in anterior abdominal distension. As soon as possible a sufficient volume of air should be suctioned off to moderately deflate the stomach. During most gastric examinations, both air insufflation and suction are commonly used to maintain a proper and safe balance of distension.

Several observations should be made during the initial examination of the stomach. These include the presence of fluid or ingesta, the ease with which the gastric walls distend when air is insufflated, and the gross appearance of the rugal folds and mucosa.

In most properly fasted patients the stomach is completely empty. Occasionally a small pool of fluid is present in the fundus or at the proximal aspect of the greater curvature. This is not considered abnormal. However, the presence of larger volumes of fluid, especially green or yellow bilious fluid, may be abnormal. This finding suggests the possibility of reflux of intestinal fluid to the stomach, which may occur in animals that have undergone enemas or that have a duodenogastric reflux disorder, an intestinal obstruction, or a primary gastric motility disorder. Bile is irritating to the gastric mucosa. Thus if significant bilious fluid is retained, the gastric mucosa may appear reddened. Mucosal erythema should be noted, but the patient should not be assumed to have gastritis. The diagnosis of gastritis requires histologic evidence.

If only a small amount of fluid is present, aspiration of the fluid is probably unnecessary. If, however, a pool of fluid obscures the rugal folds, aspiration should be done. The endoscope tip should be positioned as parallel to the gastric wall as possible, and alternating suction and air insufflation should be used. When suction is applied with the endoscope tip perpendicular to the mucosa, the tendency is to draw a portion of the mucosa into the accessory channel. This delays aspiration and may cause superficial mucosal lesions. Great care should be taken when attempting to suction fluid that is present in conjunction with particulate matter such as food or foreign body debris. The accessory channel can become obstructed if debris is suctioned along with fluid. In one instance a fragment from a small pebble obstructed the accessory channel of one of my endoscopes, and it could not be dislodged. Replacement of the accessory channel was required.

As the scope is gradually advanced through the proximal stomach, the endoscopist can thoroughly evaluate the gastric body by using the control knobs to deflect the endoscope tip or by rotating the insertion tube with the right hand (torque). With the patient in left lateral recumbency and the endoscope held in a conventional manner (i.e., buttons up), the endoscopic view is predictable. The smooth lesser curvature is on the endoscopist’s right, and the rugal folds of the greater curvature are seen below and to the left (Figure 4-3). Required directional changes can usually be made with the left thumb on the inner control knob and the right hand controlling rotation (torque) of the insertion tube. In most cases, only minor directional changes are needed to provide a panoramic view. The endoscope is advanced along the greater curvature until the angulus is identified. The angulus appears as a large fold that extends from the lesser curvature. The angulus is an important landmark that separates the body of the stomach from the antrum. Once the angulus is identified, the lesser curvature can be easily differentiated from the greater curvature of the stomach. With the patient in left lateral recumbency, the antrum is directed up or away from the tabletop. As viewed from the gastric body, the angulus and entrance to the antrum usually appear as a circular or crescent-shaped orifice that is smaller than the distended body of the stomach (see Figures 4-18, D; 4-19, B; and 4-41). The endoscopist must be able to maneuver around the angulus to advance the endoscope to the antrum, pylorus, and duodenum.

Figure 4-3 The initial view as the endoscope is advanced from the esophagus into the stomach is of the greater curvature. As described in the text and in Figure 4-2, the endoscopist first pauses to insufflate air to begin distending the stomach. If the endoscope is advanced straight ahead without adequate insufflation, the scope tip will engage the gastric wall and visualization will not be possible. A, Areas of the stomach not in view (shaded) as a standard forward-viewing endoscope is advanced into the proximal stomach. A retroversion maneuver is required to completely view the cardia and fundus. B, Corresponding endoscopic image with moderate air insufflation. The rugal folds and greater curvature of the stomach are clearly visualized, and this appearance is normal. The angulus fold is not in view.

Once the angulus and proximal antrum are visualized, the endoscopist has the option of advancing directly through the pyloric canal to the duodenum or completing the gastric examination. The cardia and fundus have not yet been completely evaluated. Depending on the particular endoscope’s angle of illumination, a portion of the proximal stomach cannot be seen as the scope enters the stomach (see Figure 4-3). For the cardia and fundus to be visualized the endoscope must be retroflexed (termed retroversion or J maneuver) so that it is possible to see the portion of the scope entering through the cardia, as well as the surrounding area (Figure 4-4). The retroversion maneuver should be done either at this point or after duodenoscopy. It can be advantageous to proceed directly from the angulus to the pylorus and duodenum. The physiologic function of the pylorus is to close in response to gastric distension. When gastric distension has been kept to a minimum and the antrum is not actively contracting, the pylorus is in a relatively lax state and the endoscope can pass through it with only minimal resistance. However, if a large volume of air has been insufflated and the endoscope has been significantly manipulated in the stomach, the pylorus may be tight and difficult to traverse. In my experience this is a greater problem in large breed dogs. Also, as the endoscopist becomes more experienced, it becomes easier to maneuver through difficult areas. I usually prefer to perform at least a cursory examination of the entire stomach before proceeding to the duodenum (i.e., the retroversion maneuver is performed before advancing to the pylorus). In most cases I perform a final, more thorough gastric examination and procure biopsy specimens after duodenoscopy.

Figure 4-4 A, Schematic diagram of retroversion maneuver (J maneuver). The endoscope tip has been deflected fully in the upward direction. B, Corresponding endoscopic image. The 20-cm marker on the endoscope insertion tube is in view. There is white foam in the gastric fundus.

Retroversion (J Maneuver)

The importance of the retroversion maneuver is that it provides an en face view of the angulus and the cardia and fundus. On forward view after the endoscope is advanced from the esophagus to the stomach, only a tangential view of the angulus is obtained, and the cardia and part of the fundus are not seen at all. Failure to thoroughly examine the proximal stomach may cause the endoscopist to miss lesions (e.g., erosion, ulceration, or neoplasia) or a foreign body located in the cardia or fundus.

To provide an en face view of the angulus, the endoscopist must initiate the retroversion maneuver at a point proximal to or opposite the angulus (see Figures 4-24, 4-25, and 4-26). The scope is advanced along the greater curvature to the level of the distal body. The inner control knob is turned counterclockwise with the left thumb, and as the endoscope is gradually advanced, the angulus can be seen en face. Variations of normal appearance may be present (see Figures 4-18 through 4-32). The endoscope tip is then deflected upward as far as possible (full counterclockwise rotation of the inner control knob) as the scope is advanced a little farther with the right hand. This maneuver generally requires at least 180 degrees of tip deflection. Most newer endoscopes are capable of 210 degrees of upward tip deflection. This deflection provides a retroflexed view of the endoscope as it enters the stomach through the cardia (see Figure 4-4). Pulling the endoscope back once this view is attained draws the endoscope tip closer to the cardia (Figure 4-5 and see Figure 4-25). A circumferential examination of the proximal stomach is completed by rotation of the insertion tube (torque) or by turning the outer control knob in each direction for lateral deflection. Air insufflation is usually necessary to keep the proximal stomach dilated. If there is insufficient distension, the stomach walls will collapse around the endoscope and it will not be in view. During most of the examination the right hand is kept on the insertion tube to keep the tube in place with respect to forward and backward motion.

Figure 4-5 For a close-up view of the fundus and gastroesophageal junction, the insertion tube has been rotated 180 degrees to the left and retracted toward the esophagus.

In cats the retroversion maneuver is started when the endoscope tip is in the midbody area (see Figure 4-43). The tip is deflected upward as the endoscope is advanced. Because the working area is smaller than in most dogs, an en face view of the angulus similar to what is seen in dogs is not achieved as often in cats.

Retroversion should be reversed gradually so that the mucosa can be further inspected. The endoscopist can accomplish this by moving the deflection controls to a neutral position while the instrument tip is still in the proximal stomach. Alternatively, the tip can be advanced to the proximal antrum while it is still in the partially retroflexed configuration. This provides an additional view of the proximal stomach and lesser curvature. When the angulus comes into view, the deflection knobs are returned to a neutral position. The antrum and pylorus should then be in view.