Ocular protothecosis in Rhodesian ridgeback dog

Purpose: To describe ocular protothecosis in dog associated to soft stool and haematochezia. Methods: A 6-year-old, spayed female, Rhodesian ridgeback dog was referred to the University of Camerino, Veterinary Teaching Hospital, because of haematochezia associated to soft stool and disorientation. Physical examination showed diffuse lymphadenopathy. Ophthalmological examination in the anterior segment revealed lack of menace response and lack of direct PLR in the right eye. Fundic examination showed bullous retina detachment in the right eye, confirmed by ocular ultrasonography; the left eye was normal. Lymphoma was excluded by cytofluorimetry. Symptomatic therapy was performed for a couple of week, in addition with itraconazole for 30 days for algal infection. Because unresponsive to therapy and clinically worse, dog’s euthanasia was performed at the owner’s request. Results: In smears of lymph -node, rectal mucosa and vitreous fluid from the right eye Prototheca spp. organisms were detected. Necropsy revealed the presence of Prototheca organisms in liver, spleen and kidneys. Prototheca was also histologically detectable in the right eye along with severe granulomatous infiltration of subretinal space. Conclusion: Protothecosis is an uncommon intestinal disease in dogs in Italy. To the authors knowledge this is the first report of ocular Protothecosis in Rhodesian ridgeback dog with monolateral eye vision loss and haematochezia associated to soft stool. Support: None.