The comparative pathology of enterocolitis caused by Clostridium perfringens type C, Clostridioides difficile, Paeniclostridium sordellii, Salmonella enterica subspecies enterica serovar Typhimurium, and nonsteroidal anti-inflammatory drugs in horses

Abstract

To determine if there were significant differences produced by 5 of the most prevalent causes of equine enterocolitis, we studied retrospectively the gross and microscopic pathology of 90 cases of enterocolitis submitted to the San Bernardino laboratory of the California Animal Health and Food Safety Laboratory. Included were cases caused by Clostridium perfringens type C (CP; n = 20), Clostridioides difficile (CD; n = 20), Paeniclostridium sordellii (PS; n = 15), Salmonella enterica subspecies enterica serovar Typhimurium (ST; n = 20), and NSAID intoxication (NS; n = 15). Grossly, necrotizing hemorrhagic typhlocolitis was seen most frequently in cases of CD, ST, and NS disease. Cases of CP and PS had enteritis or colitis in similar percentages. Congestion, hemorrhage, and pleocellular inflammatory infiltrates followed by mucosal and submucosal necrosis were the main lesions found in horses with enteritis or colitis produced by any of the etiologic agents investigated. Severe lesions were more frequent in cases of CD and CP than in cases associated with any of the other 3 etiologies. Pseudomembranes were observed with similar prevalence in the small intestine and colon affected by all agents studied. Thrombosis of the lamina propria and/or submucosa was observed in ~50% of the cases of enteritis and colitis by all etiologies, except for PS, in which the majority of the cases had thrombosis. Gross and microscopic lesions of enterocolitis were not sufficiently specific for any of these etiologic agents to enable these enteritides to be distinguished by gross and/or histologic examination.

Clostridial Diseases of Horses: A Review

“…Histopathology. Histologically, CDAD causes an array of changes in the intestinal mucosa similar to other causes of enterocolitis in horses [14]. There is necrosis of the surface epithelium with pseudomembrane formation, congestion and hemorrhage, variable numbers of neutrophils and mononuclear leukocytes in the lamina propria and submucosal edema (Figure 2C,D) [14,20].…”

“…There is usually a diffuse dark red discoloration in the serosa and mucosa of the affected segments, and pseudomembrane formation is frequently described (Figure 2A,B) [32]. In a recent study that examined gross and microscopic lesions in 90 cases of enterocolitis by different causes, necrosis and hemorrhage of the large intestinal mucosa was reported significantly more often in CDAD than in other diseases [14]. Thickening of the entire wall by edema with a gelatinous aspect was once considered specific of CDAD, although this may also occur with other causes of enterocolitis in horses [14].…”

“…Fibrinonecrotic pseudomembranes are appreciated microscopically in some cases (Figure 1C). Leukocytic infiltration is not a prominent feature of the histopathology associated with C. perfringens type C infection [14]. Numerous Gram-positive rods that are positive for C. perfringens immunohistochemistry (IHC) (Figure 1D) are often noted along the mucosal surface in affected segments of intestine.…”

“…In a recent study that examined gross and microscopic lesions in 90 cases of enterocolitis by different causes, necrosis and hemorrhage of the large intestinal mucosa was reported significantly more often in CDAD than in other diseases [14]. Thickening of the entire wall by edema with a gelatinous aspect was once considered specific of CDAD, although this may also occur with other causes of enterocolitis in horses [14]. In addition, extraintestinal lesions related to endotoxemia or septicemia such as congestion and hemorrhages in multiple organs, pulmonary edema and congestion, or hepatic necrosis may be seen [14,20].…”

“…Thickening of the entire wall by edema with a gelatinous aspect was once considered specific of CDAD, although this may also occur with other causes of enterocolitis in horses [14]. In addition, extraintestinal lesions related to endotoxemia or septicemia such as congestion and hemorrhages in multiple organs, pulmonary edema and congestion, or hepatic necrosis may be seen [14,20].…”