Isospora bigemina

I·sos·po·ra bi·gem·'i·na

a species that occurs in the small intestine of the dog, cat, fox, mink, and possibly other carnivores; the most pathogenic coccidium in dogs and cats, causing enteritis and diarrhea; the oocysts are usually sporulated when passed in the feces but are indistinguishable from those of Toxoplasma gondii, so considerable question remains as to the status of these parasites.