Prolonged survival of 3 dogs with Prototheca bovis infection treated with posaconazole

Primary enteric or disseminated infections with Prototheca bovis in dogs typically are associated with short survival times despite treatment. We describe the extended clinical course of 3 dogs diagnosed with enteric P. bovis infection treated with antifungal therapy incorporating posaconazole. One dog was alive 45 months after starting treatment, exhibiting only mild, intermittent diarrhea and no detectable algae on rectal cytology. This dog also received SC amphotericin B (AMB) infusions during the first month after diagnosis. The second dog, managed exclusively with posaconazole, was alive after 39 months with moderate mixed-bowel diarrhea and ongoing P. bovis shedding but without clinical signs of dissemination. The third dog survived 21 months before death because of central nervous system dissemination; additional treatments included itraconazole, AMB, terbinafine, and immunotherapy using an autologous vaccine. Posaconazole was well tolerated in all dogs and can be considered a therapeutic option for dogs with enteric protothecosis.