Gastroduodenal ulceration in small animals is a complex and important comorbidity that occurs when the physiological homeostasis of the gastrointestinal tract is disrupted secondary to administration of medications or the presence of local or systemic diseases. The aim of this article is to provide a comprehensive review of the veterinary literature regarding the pathophysiology, epidemiology, and risk factors associated with gastroduodenal ulceration in small animals. Pertinent concepts from the human literature will be integrated into the discussion. This article serves as an introduction to the second part of this series, which will review current evidence regarding the use of H2-receptor antagonists and proton pump inhibitors in small animals.

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Case series summaryThis case series documents ultrasonographic and clinicopathologic features of four cats with marked segmental dilatations of the common bile duct (CBD). All cats had additional ultrasonographic changes to the hepatobiliary system, including hepatomegaly, tubular to saccular intra/extrahepatic biliary duct dilatation and biliary debris accumulation. Based on all available data the presence of extrahepatic biliary duct obstruction (EHBDO) was ruled out in 3/4 cases and was equivocal in one case. One cat underwent re-routing surgery to address the CBD dilatation after multiple recurrent infections, one cat was euthanized and had a post-mortem examination and two cats were medically managed with antibiotics, liver protectants, gastroprotectants and cholerectics.Relevance and novel informationThe ultrasonographic features of the CBD in this population of cats were supportive of choledochal cysts (CCs). The maximal diameter of the CBD dilatations exceeded 5 mm in all cases, a sign that has been previously reported to be consistent with EHBDO. In our study, dilatations were segmental rather than diffuse. Given the high morbidity and mortality associated with hepatobiliary surgery in cats, segmental dilatation of the CBD should not prompt emergency surgery. Some cats may respond to medical management. Careful planning for cyst resection was beneficial in one cat. Evaluation of CC morphology (eg, size, location, concurrent intrahepatic anomalies) may assist in selecting cats that could benefit from surgical intervention.

Objectives The aim of the study was to report the ultrasonographic and clinicopathological findings in cats with confirmed pyloroduodenal adenomatous polyps. Methods Clinicopathological data, ultrasonographic and histopathological findings were collected retrospectively from medical records. Results Pyloroduodenal polyps appeared as small moderately echogenic and homogeneous nodules filling most of the proximal duodenal or pyloroduodenal lumen. The most common presenting signs in this study included acute vomiting and anorexia in 4/6 cats and lethargy in 3/6 cats. Two cats presented with severe anemia, suggestive of active bleeding. One cat presented with increased bilirubin without anemia, suggestive of impaired bile flow. Five cats survived surgical removal of the polyp and were free of clinical signs 817 days after the procedure. Conclusions and relevance Pyloroduodenal polyps have subtle ultrasonographic changes that can easily be mistaken for ingesta. They are characterized by a discrete small (up to 1.5 cm in diameter) homogeneous echogenic nodule filling the pyloroduodenal lumen. Pyloroduodenal polyps are benign lesions but can cause severe clinical signs including gastrointestinal bleeding or biliary obstruction. The prognosis is excellent with surgical removal.

In the first part of this review, we discussed the pathophysiology and epidemiology of gastric acid secretion and the epidemiology of gastroduodenal ulceration in dogs and cats. In this section, we discuss the pharmacology and evidence-based clinical use of histamine-2 receptor antagonists and proton pump inhibitors.