Gastric Candidiasis in Five Horses: A Case Series

Abstract

Candida spp. are ubiquitous yeasts that are part of most mammals' microbiota and can become opportunistic pathogens under predisposing conditions. Interestingly, recent studies in human medicine report an increased abundance of Candida spp. in association with inflammatory bowel disease (IBD). Gastrointestinal candidiasis has been primarily reported in neonatal foals, but not in adult horses. The aim of this study is to describe the morphological, histopathological, and microbiological features of gastric lesions associated with Candida infiltration in five horses referred to two tertiary hospitals for different reasons. Clinical features, findings from gastroscopy, gastric, and duodenal biopsies, as well as fungal and bacterial cultures obtained from gastric lesions will be reported. Macroscopically, gastric lesions showed a characteristic yellow/white pseudo-membranous appearance, similar to lesions reported in foals. The presence of Candida spp. was confirmed by positive culture and/or histopathological evidence of fungal infiltration on the gastric epithelium. Three out of five horses showed histopathological changes in duodenal biopsies, potentially suggesting IBD. These results demonstrate that gastric candidiasis can occur in adult horses. Further research is needed to elucidate the pathogenesis, predisposing factors, and clinical relevance of Candida spp. infections in the equine stomach, as well as their potential impact on gastrointestinal health and overall performance.

Keywords: Candida; colic; equine; gastrointestinal; inflammatory bowel disease; microbiota; omeprazole; stomach; ulcer; yeast.

Figure 1

Gastroscopic images showing white, cotton-like material on the squamous mucosa of horses with gastric candidiasis, forming pseudo-membranous multifocal to coalescing plaques (A–C). In some cases, fungal lesions appeared punctiform (D), ring-shaped (E) or with a miliary appearance (F), close to the greater curvature. An underlying hyperemic area, extending beyond the plaques, is visible in some lesions (E,F).

Figure 2

Histopathological images of the endoscopic biopsies taken from the white plaques on the squamous mucosa of horses with gastric candidiasis. Periodic acid-Schiff stain. (A) Squamous epithelium with fungal spores and hyphae, pyocytes, and bacteria (10×). (B) Numerous spores and hyphae colonizing the squamous epithelium of the equine stomach (40×).