Cryptosporidiosis in a pup.

Cryptosporidiosis is a coccidian parasitism which has been implicated as a cause of diarrhea in man and a variety of animals. Cryptosporidiosis was diagnosed in a one-week-old pup which had a history of acute diarrhea. Organisms, 2 to 3 mm in diameter, covered the microvillous border of intestinal epithelium. Ultrastructurally, the cryptosporidia had one or more nuclei with prominent nucleoli and abundant cytoplasmic endoplasmic reticulum. Cryptosporidia may have played a role in the enteritis seen in this pup but further studies are needed to establish its pathogenicity.