Protothecosis is an uncommon disease caused by algae of the genus Prototheca. In dogs, the infection is usually first localized to the colon but has the propensity to later disseminate hematogenously to many other organs, with marked tropism for the eyes and central nervous system. Diagnosis is established by culture and/or evidence of Prototheca organisms in cytologic or histologic preparations. Species characterization, however, requires molecular investigations. Our laboratory set up a real-time PCR targeting portion D1/D2 of the 28S rRNA for identification of Prototheca species from both positive cultures (of rectal swabs and urine) and formalin-fixed, paraffin-embedded tissue. Prototheca bovis, P. ciferrii, and P. wickerhamii were characterized in 11 dogs with systemic or cutaneous protothecosis. Prototheca identifications were phylogenetically consistent with the new taxonomy proposed for this genus based on the mitochondrial cytochrome b gene. As a pilot study, we screened feces and rectal scrapes from 200 asymptomatic dogs, using 2 cohorts of stray and owned animals, to determine the prevalence of intestinal carriage of Prototheca spp. The Prototheca-negative results from both cohorts of healthy dogs suggest that predisposing factors related to the host probably contribute more to the acquisition of clinical disease than exposure to contaminated environments.

Protothecosis是由藻类属一种罕见的疾病绿藻。在狗中，感染通常首先定位于结肠，但有随后通过血行传播到许多其他器官的倾向，对眼睛和中枢神经系统具有明显的趋向性。诊断是通过细胞学或组织学标本中的培养和/或无绿藻生物体的证据确定的。然而，物种表征需要分子调查。我们的实验室建立了一个实时 PCR 靶向部分 D1/D2 的 28S rRNA，用于从阳性培养物（直肠拭子和尿液）和福尔马林固定、石蜡包埋的组织中鉴定Prototheca物种。绿藻牛，毕赤酵母和P. wickerhamii在 11 只患有全身性或皮肤原虫病的狗中进行了表征。Prototheca鉴定在系统发育上与基于线粒体细胞色素b基因为该属提出的新分类法一致。作为一项试点研究，我们使用 2 组流浪动物和自有动物筛查了 200 只无症状狗的粪便和直肠擦伤，以确定Prototheca属的肠道携带率。两组健康犬的Prototheca阴性结果表明，与宿主相关的易感因素可能比暴露于受污染的环境更有助于获得临床疾病。