Lawsonia intracellularis is an obligate intracellular bacterium causing proliferative enteritis in a broad range of species.1-5 A 2.5-yr-old Japanese macaque (Macaca fuscata) was presented for vomiting and mild depression. Radiographs indicated metallic foreign body ingestion. A thickened ileum was found during exploratory laparotomy. Biopsies of the thickened ileum revealed severe, chronic, pyogranulomatous and lymphocytic enteritis, and presence of spindle-shaped organisms on sliver stain (Warthin Starry). Immunohistochemistry and PCR of the ileal biopsy were positive for Lawsonia intracellularis. The animal developed severe hypoproteinemia and pitting edema. It recovered 42 days after presentation with a treatment regime including azithromycin and hetastarch. Enteropathies are common in nonhuman primates and difficult to diagnose. L. intracellularis should be included in the differential list. The zoonotic potential of this bacterium should be considered.
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