Clinical management and case review of a presumptive novel clinical presentation of protothecosis in donkeys causing ulcerated nodular lesions in the ear pinnae of 18 animals

This is a retrospective case series that describes a novel syndrome seen in 18 donkeys in Morocco that presented to this author,'s clinic with ulcerated nodular lesions of the ear pinnae. In the majority of cases, the lesions are confined to the ears, they are always bilateral and can occasionally progress to other areas of the body. Macroscopically, the lesions in all 18 donkeys are very uniform in presentation, even if the size of the nodules varies. This case series reviews the presentation, investigation, treatment and outcome for 18 cases presented to these authors’ clinics from 2011 to 2021. Skin biopsies from a subset of eight cases showed similar changes in chronic pyogranulomatous, dermatitis with myriad intra‐ and extra‐histiocytic organisms, the morphology of which is most consistent with that of Prototheca spp. infection. This is a novel presentation that represents a significant welfare issue for donkeys, as well as having important economic consequences for owners in the developing world.