Duodenitis-Proximal Jejunitis in Horses After Experimental Administration of Clostridium difficile Toxins

Abstract

Background: Duodenitis-proximal jejunitis (DPJ) is an acute sporadic gastrointestinal disorder of horses of unknown cause.

Hypothesis/objectives: We hypothesize that Clostridium difficile toxins are involved in the pathogenesis of DPJ in horses. The objective of this study was to determine whether experimentally delivered C. difficile toxins cause clinical signs and histologic lesions similar to those of naturally occurring DPJ.

Animals: Six healthy mature mixed breed horses.

Methods: Experimental study: animal model of animal disease. Fasted horses were administered crude C. difficile toxins via gastroscopy and monitored for up to 48 hour. Blood was collected for complete blood cell count, biochemistry profile, and plasma fibrinogen assay, and abdominal fluid was collected for cytologic analysis and total solids before and after toxin administration. Physical examination and abdominal ultrasonography were performed throughout the study period. Tissues were collected from the gastrointestinal tract and processed for routine histologic analysis, and lesions were scored.

Results: Clinical signs were observed in 2 of 6 horses that are typical although not specific for horses with naturally occurring DPJ. Histopathologic lesions were observed in 6 of 6 horses and were similar to those reported in horses with naturally occurring DPJ. Two horses were severely affected.

Conclusions and clinical importance: Duodenitis-proximal jejunitis is likely a syndrome with multiple causes that result in the same clinical and pathologic findings, and our data suggest that the toxins of C. difficile represent one cause of this syndrome. Toxin dose and variation in individual animal susceptibility might affect the clinical signs and lesions after administration of C. difficile toxins.

Keywords: Enteritis; Exotoxins; Gastrointestinal.

Figure 1

Gross lesions in a horse inoculated with Clostridium difficile toxins. Small‐intestinal loops have multiple areas of hyperemia and congestion visible on the serosal surface (A). In an opened section of duodenum, there is diffuse hemorrhage as well as thickening and corrugation of the mucosal surface (B). Lesions presented are from horse 5.

Figure 2

Microscopic lesions in the duodenum of a horse inoculated with Clostridium difficile toxins. In (A), there is blunting of villi with loss of epithelium lining villous tips. The lamina propria is expanded by congestion and hemorrhage. The lumen contains inflammatory cells intermixed with sloughed epithelial cells, erythrocytes, and fibrin. Magnification 10×, hematoxylin and eosin (H&E) stain. In (B), the intact epithelial cells are flattened and stretched across the surface of an affected villus. Magnification 40×, H&E stain. Lesions presented are from horse 5. Figure A length of the scale bar = 100 μm. Figure B length of the scale bar = 25 μm.