ULTRASONOGRAPHIC FINDINGS IN CANINE GASTRIC NEOPLASIA IN 13 PATIENTS

The ultrasonographic findings in 13 canine patients with histopathologically proven gastric tumors were reviewed. The echogenicity of gastric wall lesions was variable and independent of the type of tumor. All dogs had an increase in gastric wall thickness and in only one dog was the wall layering intact. Regional lymph node involvement was a common finding, but abnormalities within the liver were seen in only one patient. Gastric neoplasia was observed most commonly in middle-aged and old, medium- to large-sized dogs. Carcinoma was the most common tumor found. In this study, with a limited number of animals and limited tumor types, it appeared that thickening of the gastric wall, accompanied by loss of gastric wall layering and enlargement of regional lymph nodes were ultrasonographic signs likely to be found with gastric neoplasia. In this limited study the histologic type of gastric tumor could not be predicted on the basis of the ultrasound examination.     

Ultrasonographic appearance of primary gastric neoplasia in 21 dogs

The ultrasonographic findings in 21 dogs with histologically confirmed primary gastric neoplasia were reviewed. Location, shape of the gastric lesion, evidence of gastric wall thickening, wall layers affected, presence of ulceration, evidence of extension through the gastric wall and lymphadenopathy were recorded. Twelve dogs with carcinoma shared many ultrasonographic features with six dogs that had lymphoma, the majority having sessile masses that appeared to involve all layers of the gastric wall; many also had evidence of ulceration and lymphadenopathy. Signs of extension of the lesion through the serosal surface of the stomach were identified ultrasonographically only in dogs with carcinoma. In contrast, three dogs with leiomyoma or leiomyosarcoma each had a focal mass affecting the gastric antrum, and lymphadenopathy was not identified ultrasonographically in these dogs. Even without any specific patient preparation, ultrasonography enables a morphological assessment of gastric neoplasms that may prompt a tentative diagnosis of gastric neoplasia and stimulate further investigation.     

ULTRASONOGRAPHY OF CANINE GASTRIC EPITHELIAL NEOPLASIA

Signalment, clinical and ultrasonographic findings from 16 dogs with histologically confirmed gastric epithelial neoplasia were reviewed. The most common clinical findings were vomiting, anorexia and weight loss. Hematemesis and melena were uncommon findings. Ten (10/16) dogs were female and there were four Chows. The most common ultrasonographic findings were transmural thickening of the gastric wall associated with altered wall layering. A poorly echogenic lining often was noted on the innermost and/or the outermost portions of the gastric wall, separated by a more echogenic central zone. The distribution of these changes was variable. This ultrasonographic feature, called pseudolayering, was present in 14 dogs. It was believed to most likely correlate to the unevenly layered tumor distribution noted histopathologically. The maximum wall thickening ranged from 1 cm to 2.7 cm. Regional lymphadenopathy was identified ultrasonographically in 15 dogs. Ultrasound-guided fineneedle aspiration biopsy or automated microcore biopsy, endoscopic biopsy, surgical biopsy or necropsy resulted in the diagnosis of carcinoma in 15 dogs and of carcinoid tumor in one dog. The results of this study suggested that ultrasonography was a useful tool for the detection and diagnosis of canine gastric epithelial neoplasia. Furthermore, ultrasonography can assist in obtaining diagnostic samples and in clinical staging of the tumor.     

Stomach wall evaluation using helical hydro-computed tomography

In helical hydro-computed tomography (helical hydro-CT), water is used as a neutral luminal contrast medium together with intravenous iodine contrast medium for the diagnosis and staging of human gastric neoplasia. We evaluated the feasibility of helical hydro-CT in 11 healthy animals (nine dogs and two cats). Adequate uniform gastric distension was obtained with 30 ml water/kg body weight. Fourteen client-owned dogs and four cats with suspected or diagnosed gastric neoplasia then underwent helical hydro-CT followed by intravenous contrast medium administration. Focal thickening with moderate contrast enhancement was found in 10 dogs and 3 cats. The extent of the lesion was assessed easily in all these patients. Three dogs and one cat had a normal stomach wall. One dog had multifocal thickening of the antrum but no histopathologic diagnosis was made. Helical hydro-CT, followed by intravenous contrast medium administration, is a simple technique for assessing the stomach wall.     

GASTRIC LYMPHOSARCOMA IN A DOG: A CASE REPORT

A 9-year-old female spayed mixed-breed dog was presented with a ten-week history of vomiting. A survey abdominal radiograph showed a soft tissue mass on the lesser curvature of the stomach and an adjacent thickened greater curvature. A barium contrast study confirmed the presence of this mass. The radiographic diagnosis was gastric tumor. Radiographic signs of gastric neoplasia include soft tissue masses or thickening of the stomach wall, delayed gastric emptying, immobility of portions of the stomach wall, and residual stomach-wall staining by barium. Necropsy revealed a gastric lymphosarcoma that had infiltrated the entire circumference of the pyloric antrum. The most common gastric malignancy in the dog is adenocarcinoma. Gastric lymphosarcoma is considered rare.     

A RETROSPECTIVE STUDY INTO THE EFFECTS OF OPERATOR EXPERIENCE ON THE ACCURACY OF ULTRASOUND IN THE DIAGNOSIS OF GASTRIC NEOPLASIA IN DOGS

The accuracy of three diagnostic techniques in two separate time periods was examined. In the first time period, 18 dogs were referred to the University of Bristol with signs suggestive of gastric neoplasia. Of these 18 dogs, 7 had a positive diagnosis of gastric neoplasia from histopathology samples (38% prevalence). The sensitivity of ultrasound was found to be 42.9% with a specificity of 63.6%. A year later the study was repeated with 40 cases referred for investigation. Of these 40 dogs, 16 had a positive histopathologic diagnosis of gastric neoplasia (40% prevalence). At this time the sensitivity of ultrasound had increased to 81.3 % and the specificity had increased to 70.8 %. The increase in sensitivity was attributed to an increase in operator experience in the performance of the ultrasound examination. This improvement in sensitivity and experience resulted in a greater accuracy at detecting the presence of gastric neoplasia.     

Gastric neoplasia.

Gastric tumors are rare in dogs and cats but should always be considered, particularly in older dogs with chronic vomiting. The most common gastric tumor in dogs is carcinoma, although lymphoma is rare. Breeds that seem to be predisposed to gastric carcinoma are the Rough Collie, Staffordshire Terrier, and Belgian Shepherd. Lymphoma is the most common gastric malignancy in cats. Contrast radiographic examination and endoscopy are the elective procedures of choice for the diagnosis of these conditions. Biopsy is essential to confirm the diagnosis. Surgery is the only potentially curative modality for localized gastric carcinoma. Chemotherapy alone or following surgery is the elective treatment of choice for gastric lymphoma in dogs and cats. The prognosis is poor for both types of tumor, but prolonged survival times in individual animals are possible.     

COMPARISON OF THE EFFECT OF LAPAROSCOPIC AND CONVENTIONAL PYLORIC SURGERY ON GASTRIC EMPTYING IN DOGS

The effect of a laparoscopic approach and pyloric surgery on canine gastrointestinal activity, particularly gastric emptying time, is not well understood. The purpose of this study was to compare the effect of laparoscopic and conventional pyloric surgery, in Ramstedt pyloromyotomy and Heineke-Mikulicz pyloroplasty, on complete gastric emptying time in 20 clinically normal dogs. Dogs were divided into four groups of five animals: dogs with laparoscopic Ramstedt pyloromyotomy, conventional Ramstedt pyloromyotomy, or laparoscopic Heineke-Mikulicz pyloroplasty, and the conventional Heineke-Mikulicz pyloroplasty group. Gastric emptying time using barium sulfate mixed with dry kibble dog food was measured fluoroscopically before and 1 month after surgery. Gastric emptying of solids was significantly enhanced in the pyloroplasty groups in the postoperative period compared with preoperative emptying. Just as after conventional pyloromyotomy, gastric emptying time after laparoscopic pyloromyotomy was not statistically different as compared with preoperative values. This study indicates that the fluoroscopic test meal is a valuable tool for defining complete gastric emptying time in normal dogs. We conclude that pyloromyotomy was less effective in decreasing complete gastric emptying time than Heineke-Mikulicz pyloroplasty in normal dogs. The possibility of decreasing complete gastric emptying time by laparoscopic surgery suggests a potential clinical application for this technique in small animals.     

Gastric neoplasms in the dog: a report of 20 cases.

Twenty dogs with gastric tumors were admitted to the University of Minnesota Veterinary Hospital and Diagnostic Laboratory from 1951 to 1974. The tumors included 14 carcinomas, 3 lymphosarcomas, 2 leiomyomas, and 1 leiomyosarcoma. The carcinomas were categorized morphologically as carcinoma (5), adenocarcinoma (2), scirrhous carcinoma (5), and scirrhous adenocarcinoma (2). Most of the tumors were located in the body and pylorus. Ulceration occurred in 11 dogs, with 2 ulcers penetrating and resulting in peritonitis. Metastasis occurred in 4 of the dogs. The mean age of the dogs was 9.7 years. The male-to-female ratio was 12 to 8. There was no significant breed predominance. The mean duration of illness was 2.14 months. Radiographic features were consistent with gastric neoplasia in 2 of 6 dogs radiographed.     

Gastric extramedullary plasmacytoma in a dog.

A 10-year-old mixed-breed dog was examined because of a 6-week history of daily vomiting and sporadic diarrhea. On gastroscopy, a crateriform mass was observed on the greater curvature of the stomach. Partial gastrectomy and lymphadenectomy of a large mesenteric lymph node was performed. Gastric plasmacytoma with lymph node metastasis was diagnosed by histologic and immunoperoxidase methods, and chemotherapy was initiated with doxorubicin hydrochloride and diphenhydramine hydrochloride. The dog remains clinically normal 30 months after initial diagnosis. Although gastric plasmacytomas are rare in dogs, long-term survival appears to be better with this disease than with other types of gastric neoplasia.     

Gastric Neoplasia in Horses

Background: Gastric neoplasia of horses is incompletely described.
Objective: Provide history, clinical signs, and clinicopathological and pathological findings associated with gastric neoplasia in horses.
Animals: Twenty-four horses with gastric neoplasia.
Methods: Retrospective study. History, clinical signs, and clinicopathological and pathologic findings in horses diagnosed histologically with gastric neoplasia were reviewed.
Results: Horses ranged in age from 9 to 25 years (median 18 years at presentation). There was no apparent breed or sex predisposition. The most common presenting complaints were inappetance (17/24), weight loss (14/24), lethargy (7/24), hypersalivation (7/24), colic (5/24), and fever (5/24). The most consistent clinical signs were tachypnea (10/19), decreased borborygmi (8/19), and low body weight (7/17). Useful diagnostic tests included rectal examination, routine blood analysis, gastroscopy, abdominocentesis, and transabdominal ultrasound examination. Anemia was the most common hematologic abnormality encountered (7/19), and hypercalcemia of malignancy was seen in 4/16 horses. Squamous cell carcinoma was the most common tumor identified (19/24), and was most often (14/19) found as a single ulcerated, necrotic mass in the nonglandular portion of the stomach. Other gastric neoplasms encountered were leiomyoma (n=2), mesothelioma (n=1), adenocarcinoma (n=1), and lymphoma (n=1). Metastatic neoplasia was found in 18/23 horses. The median time from onset of clinical signs to death was 4 weeks, and all horses died or were euthanized because of gastric neoplasia.
Conclusions: Squamous cell carcinoma is the most common primary gastric neoplasia in horses. The survival time after diagnosis of gastric neoplasia in horses is short.     

Ultrastructure of the hydrophobic gastric surfactant barrier in the dog

OBJECTIVES: To confirm the hydrophobicity of the luminal surface of the canine stomach and to elucidate the ultrastructure of the lining imparting that property. DESIGN AND PROCEDURES: Gastric and duodenal mucosal samples from eight dogs were collected immediately after euthanasia and subjected to contact angle measurement using a goniometer. Other samples were examined by electron microscopy following a fixation procedure known to preserve phospholipids and oligolamellar structures. RESULTS: Contact angles for the canine gastric mucosal surface (85.1 +/- 5.5) were significantly greater (P < 0.0001) than for the duodenum (24.0 +/- 1.7). Electron microscopy revealed the existence of surfactant as abundant osmiophilic phospholipid material within the gastric and duodenal mucosae. CONCLUSION: We have confirmed the hydrophobic nature of the canine gastric mucosa whereas the luminal surface of the duodenum is hydrophilic. We propose that the water-repellent nature of the canine gastric lining contributes to the 'gastric mucosal barrier' and is imparted by an oligolamellar layer of surface-active phospholipid ('gastric surfactant') adsorbed to the surface. Both gastric and duodenal mucosae may also utilise phospholipids as an intercellular defense mechanism in the event that tight junctions are breached by acid. It is tempting to speculate that a deficiency of gastric phospholipids may predispose dogs to ulcers. Further, exogenous administration of phospholipids may be useful in preventing gastric ulceration.     

Tube gastrostomy in dogs

Tube gastrostomy was performed in 19 dogs over a period of 36 months. Indications for tube gastrostomy included non-oral feeding for the management of oesophageal injuries (nine cases) and dysphagia resulting from oral or pharyngeal trauma (two cases) and decompression and, or, gastropexy for gastric diseases including gastric dilatation volvulus (four cases), gastric outflow diseases (three cases) and gastric neoplasia (one case). All the tubes were placed surgically and left in situ for periods of up to 14 days. Feeding was by frequent bolus administration of a proprietary enteral food initially followed by homogenised commercial dog food. The tubes were readily managed and patency maintained in all cases. Gastric stomata granulated within three days of tube removal. Fourteen dogs recovered and returned to normal oral feeding while three died as the result of their presenting condition. A fourth was euthanased four months after surgery because of recurrence of a gastric malignancy. This review indicates that surgically placed tube gastrostomy is readily performed and is an effective means of providing non-oral alimentation and, or, gastric decompression.     

Gastric and intestinal surgery.

Gastric surgery is commonly performed to remove foreign bodies and correct gastric dilatation-volvulus and is less commonly performed to treat gastric ulceration or erosion, neoplasia, and benign gastric outflow obstruction. Intestinal surgery, although commonly performed by veterinarians, should never be considered routine. The most common procedures of the small intestinal tract performed in dogs and cats include enterotomy and resection/anastomosis. Surgery of the large intestine is indicated for lesions causing obstruction, perforations, colonic inertia, or chronic inflammation.     

Canine and feline emphysematous gastritis may be differentiated from gastric emphysema based on clinical and imaging characteristics: Five cases

Gastric pneumatosis is an imaging finding defined as the presence of gas foci in the gastric wall. In humans, this imaging feature can result from one of two separate clinical entities: life‐threatening emphysematous gastritis or clinically benign gastric emphysema. This retrospective case series study describes the clinical and imaging features in five animals diagnosed with spontaneous gastric pneumatosis without gastric dilatation‐volvulus. Three canine and two feline cases of spontaneous gastric pneumatosis were identified on radiographic and ultrasonographic examinations. In addition to gastric pneumatosis, one dog and two cats presented concomitant systemic signs such as lethargy, hematemesis, anemia, or leukocytosis. Two dogs remained asymptomatic or presented mild gastrointestinal signs. Portal gas was described in two dogs and one cat, and pneumoperitoneum in one dog. These features were not considered clinically significant. The dog and two cats with systemic signs were euthanized due to clinical deterioration and diagnosed with emphysematous gastritis. The gastric pneumatosis of both dogs without systemic signs resolved while on medical management without antibiotic therapy. These latter cases were interpreted as consistent with gastric emphysema. Findings from the current study indicated that gastric pneumatosis can occur without gastric dilatation‐volvulus in cats and dogs and that a combination of clinical and imaging characteristics may help to differentiate between potentially life‐threatening emphysematous gastritis and relatively benign gastric emphysema. More studies are needed to determine the etiology and risk factors associated with these conditions.     

Pneumatosis in Canine Gastric Dilatation-Volvulus Syndrome

Retrospectively, 243 dogs with radiographic evidence of gastric dilatation-volvulus (GDV) were studied for radiographic signs of pneumatosis (intramural gas), pneumoperitoneum, splenomegaly, and severity of gastric distention. The sensitivity, specificity, and predictive value of these imaging signs as predictors of gastric wall necrosis, as determined by visual inspection at surgery or necropsy, were determined. The sensitivity and specificity of gastric pneumatosis were 14.1% and 92.7%, respectively. The prevalence of gastric wall necrosis was 26.6%. The positive and negative predictive values of gastric pneumatosis for predicting gastric necrosis were 40.9% and 74.9%, respectively. Gastric pneumatosis and pneumoperitoneum were identified together in four dogs. Pneumoperitoneum, either alone or in conjunction with pneumatosis, yielded similar results as a test for gastric necrosis. Splenomegaly and severity of gastric distention were insensitive and nonspecific for gastric wall necrosis. Splenomegaly did not predict the need for splenectomy at surgery. Although pneumatosis and pneumoperitoneum are relatively specific signs of gastric wall necrosis, the utility of these signs as a test for gastric necrosis is limited in clinical practice. The significance of pneumatosis should be taken into consideration with previous treatments for gastric decompression, as percutaneous gastric trocharization or orogastric intubation may increase the number of false-positive results.     

Gastric dilatation-volvulus in dogs

Gastric dilatation-volvulus (GDV) is a disease in which there is gross distension of the stomach with fluid or gas and gastric malpositioning. It causes pathology of multiple organ systems and is rapidly fatal. It is common in large- and giant-breed dogs. The disease appears to have a familial predisposition. Thoracic depth/width ratio also appears to predispose dogs to GDV. Implicated dietary factors include dietary particle size, frequency of feeding, speed of eating, aerophagia and an elevated feed bowl. A fearful temperament and stressful events may also predispose dogs to GDV. Abdominal distension, non-productive retching, restlessness, signs of shock, tachypnoea and dyspnoea are possible clinical signs. Initial treatment includes treatment of shock and gastric decompression. Surgical treatment should be performed promptly. There are no studies comparing the use of different anaesthetic agents in the anaesthetic management of GDV. Pre-medication with an opioid/benzodiazepine combination has been recommended. Induction agents that cause minimal cardiovascular changes such as opioids, neuroactive steroidal agents and etomidate are recommended. Anaesthesia should be maintained with an inhalational agent. Surgical therapy involves decompression, correction of gastric malpositioning, debridement of necrotic tissue, and gastropexy. Options for gastropexy include incisional, tube, circumcostal, belt-loop, incorporating, and laparoscopic gastropexy. Expected mortality with surgical therapy is 15–24%. Prognostic factors include mental status on presentation, presence of gastric necrosis, presence of cardiac arrhythmia and plasma lactate levels. Prophylactic gastropexy should be considered in dogs identified as being at high risk.     

Gastric emptying of a radionuclide-labeled test meal after surgical correction of gastric dilatation-volvulus in dogs

Gastric emptying of a radionuclide-labeled test meal was studied in 10 dogs that had been treated surgically for gastric dilatation-volvulus and in 10 clinically normal (control) dogs. There were no significant differences between the gastric emptying rates and patterns in treated and in control dogs. Thus, there are no indications that gastric emptying is delayed in dogs that have recovered from gastric dilatation-volvulus, and there is no reason for pyloric surgery in dogs with this condition.     

Gastric function in dogs with naturally acquired gastric Helicobacter spp. infection

The association of Helicobacter pylori with gastritis, peptic ulcers, and gastric neoplasia has led to fundamental changes in the understanding of gastric disease in humans. The relationship of Helicobacter spp. infection to gastric disease in dogs is unclear. The objective of this study was to determine if Helicobacter infection affects the gastric secretory axis of dogs. Eight Beagle dogs with naturally acquired Helicobacter spp. infection were studied before and after (4 and 29 days) the attempted eradication of Helicobacter spp. with a combination of amoxicillin, metronidazole, and famotidine (AMF). Six specific-pathogen-free, Helicobacter-free Beagle dogs served as controls. The electron microscopic appearance of spiral organisms in infected dogs indicated coinfection with Helicobacter felis- and H bizzozeronii-like organisms. Unstimulated gastric pH and fasting, postprandial, and bombesin-stimulated plasma gastrin were similar in both infected and uninfected dogs, although a trend (P = .09) toward higher meal-stimulated gastrin was observed in infected dogs at 60 minutes. Pentagastrin-stimulated maximal acid output (mmol HCI/kg0.75/hour) and titratable acidity (mmol HCl/mL) were similar in both infected and uninfected dogs, but gastric pH during maximal acid output was lower (P < .01) in uninfected dogs. Mild gastric inflammation was present in both infected and uninfected dogs. Gastric spiral organisms were undetectable in 6/8 infected dogs 4 days after AMF but had recurred in 8/8 dogs 29 days after AMF. Analysis of gastric DNA with Helicobacter-specific primers indicated persistence of Helicobacter DNA at 4 and 29 days after antibiotic therapy. Acid secretion, plasma gastrin, and mucosal inflammation were not affected by the transient suppression of Helicobacter spp. by AMF. These findings suggest that gastric secretory function in dogs is not markedly perturbed by naturally acquired Helicobacter spp. infection and that treatment with amoxicillin, metronidazole, and famotidine causes suppression rather than eradication of gastric Helicobacter spp. in dogs.     

EVALUATION OF THE GASTROINTESTINAL TRACT IN DOGS USING COMPUTED TOMOGRAPHY

Abdominal computed tomography (CT) studies of 19 dogs with no history or clinical signs of gastrointestinal disease, and two dogs with a histological diagnosis of gastrointestinal neoplasia were examined retrospectively. Gastrointestinal segments were evaluated subjectively for conspicuity, contrast enhancement, and wall layering after contrast medium administration. In dogs without gastrointestinal disease, there were 62.8% of gastrointestinal segments (serosa to serosa) and 77.7% of gastrointestinal walls (serosa to mucosa) visualized. Wall layering on postcontrast images was seen in 21.8% of gastrointestinal segments. There was significant association between gastrointestinal diameter and wall thickness. There was significant association between weight and gastrointestinal wall thickness in the following regions: gastric fundus, gastric body, gastric pylorus, gastric pyloric antrum, duodenal cranial flexure, jejunum and ascending colon, and between patient weight and gastrointestinal diameter in cranial duodenal flexure, descending duodenum, transverse duodenum, ascending duodenum, and jejunum. Measurements acquired from CT studies correlated well with previously published normal reference ranges for radiographic and ultrasonographic studies. Gastrointestinal neoplasia, diagnosed in two dogs, had a gastrointestinal wall thickness greater than the range of the dogs without gastrointestinal disease. Computed tomography offers identification of the gastrointestinal tract segments in dogs, allows for evaluation of gastrointestinal diameter and aids in investigation of gastrointestinal wall thickness.