Systemic Candidiasis in an Apparently Immunocompetent Dog

Members of the family Candida spp. are ubiquitous dimorphic fungi that normally inhabit the alimentary, upper respiratory, and genital mucosae of mammals. Cell-mediated immunity appears to be an important limitation to the pathologic spread of these fungi. Prolonged immunosuppression, cytotoxic chemotherapy causing neutropenia, diabetes mellitus, long-term glucocorticoid therapy, and prolonged antimicrobial therapy have resulted in an increased incidence of both localized and disseminated candidiasis. This report describes a systemic Candida spp. infection in a dog with no obvious underlying deficiency in host resistance. Cytopathology, histopathology, transmission electron microscopy, and immunohistochemical staining were used to determine the etiology of the causative agent.