We hypothesized that (i) serum gastrin concentrations are higher in acid-suppressant-treated dogs with CE compared to those dogs not receiving any antisecretory treatment, and that serum gastrin can help to separate dogs with CE from dogs with gastrinoma (historical positive controls); (ii) serum gastrin concentrations are correlated with the severity of clinical signs and with microscopic lesions in the stomach and duodenum; and (iii) use of a population-based RI for serum gastrin concentration is appropriate. The gene discussed is GAST; the disease is gastrin-producing neuroendocrine tumor.