A concurrent outbreak of infection by canine parvovirus 2b (CPV-2b) and Clostridium difficile producing A and/or B toxins occurred in Asian small-clawed otters (Amblonyx cinereus). The 5 clinically affected otters were 6- to 24-mo-old intact females that had severe diarrhea, dehydration, were acutely comatose, and died 1-4 d after the onset of clinical signs. Postmortem examination was performed in 3 of 7 otters. Macroscopically, the small intestine was diffusely reddened and contained red-to-brown, malodorous, watery digesta without formed feces (3 of 3). Histologic examination identified loss of enterocytes and necrosis of crypt epithelial cells. Denuded villi were often covered by mixed bacterial colonies with a predominance of gram-positive cocci to short rods in addition to larger gram-positive and -negative rods. There was also splenic lymphoid follicle depletion (2 of 3). Immunofluorescence assay revealed CPV antigen in enterocytes (2 of 3), mesenteric lymph nodes (3 of 3), and spleen (1 of 3). Immunohistochemistry revealed CPV antigen in enterocytes, lymphocytes, and dendritic cells of the Peyer patches and spleen (3 of 3), and lingual epithelial cells (1 of 2). CPV was isolated from tissues from 2 of 3 otters, and DNA sequencing identified CPV-2b for the 1 isolate tested. C. difficile producing A and/or B toxins were identified in the intestinal content by ELISA (3 of 3). To our knowledge, an outbreak of CPV-2b infection and C. difficile with clinically significant gastrointestinal disease has not been described previously in otters. The source of the viral infections remains unknown; however, these agents should be considered in otters and other mesocarnivores with similar clinical and pathologic findings.