Proventriculitis and ventriculitis associated with zygomycosis in ostrich chicks

This report describes eight cases of proventriculitis and ventriculitis in ostrich chicks less than 2 months old. Clinical signs included acute onset of lethargy and anorexia in three cases, and chronic weight loss with lethargy and anorexia in four cases; no history was available in one case. There was limited antibiotic therapy in two cases; a third case was treated for giardiasis. Concurrent bacterial, yeast, and viral infections were common. Lymphoid depletion and/or necrosis of bursa, thymus, and spleen suggested severe immune challenge or immunosuppression in many cases. Histologically, there was severe ulcerative proventriculitis and ventriculitis with intralesional fungal hyphae. In two chicks with granulomatous pneumonia, similar fungal hyphae were also observed in the lung. Fungal hyphae were rarely septate, with irregular, non-parallel walls, and ranged in diameter from 7 to 20 microns. Occasional globoid distentions of the hyphae were present. Fungi were identified morphologically as species in the Zygomycetes class; in one case a Mucor sp. was cultured. Zygomycetes appear to be potentially serious opportunistic pathogens of ostrich chicks.