Disseminated protothecosis in a dog.

A dog with forelimb lameness, bilateral retinal detachment, and hemorrhagic diarrhea, died. Necropsy demonstrated multifocal lesions in the skeletal musculature, myocardium, liver, thyroid glands, kidneys, eyes, and brain. Microscopically, the lesions contained numerous organisms and minimal cellular infiltrates. The morphologic and cultural characteristics of the organisms were similar to prototheca. The organisms in tissue sections reacted positively for Prototheca zopfii, using an indirect fluorescent antibody technique.