2015 ACVIM Forum Research Abstract Program

Full thickness gastric, duodenal, jejunal, ileal, and colonic biopsies were obtained from 6 clinically normal, healthy adult dogs immediately after humane euthanasia. Immunohistochemistry was performed using commercially available rabbit and/or goat histamine-receptor antibodies predicted to react with canine tissues on formalin-fixed, paraffin embedded tissue sections using a refined avidin-biotin detection technique. Tissues were evaluated with light microscopy to identify the presence and histologic distribution of the H1, H2, H3, and H4 receptors in the gastrointestinal tract. Formalin-fixed tissue of a grade 3 canine mast cell tumor was used as a positive control. The staining intensity of the immunoreactivity of the histamine receptors in the gastrointestinal tract was qualitatively graded as: 0, negative; 1 + , weak; 2 + , moderate, and 3 + , strong. To determine if there were differences in histamine receptor scores among the superficial and deep mucosa, submucosa, lymphoid tissue, smooth muscle and ganglia of each section in the gastrointestinal tract, a method similar to the non-parametric Friedman's test was conducted.