Mammary and Systemic Aspergillosis in Dairy Sheep

Abstract

Mammary aspergillosis was diagnosed in four flocks of dairy sheep, comprising a total of 1,750 ewes. These animals had been treated prophylactically by intramammary infusion with cloxacillin 5 months prior to lambing. Mammary aspergillosis with concomitant spread to the regional lymph nodes was present in these flocks in a percentage ranging from 2% to 36.4% of treated sheep. Pathologic, bacteriologic, and mycologic studies were performed in seven of the affected ewes. Some of them also had lung, kidney, and liver involvement. The pathologic reaction within lesions ranged from the acute to subacute type, dominated by necrosis and vasculitis with thrombosis, to the chronic granulomatous type, with macrophages and giant cells. The distribution of lesions and the presence of a remarkable vasculitis with fungal thrombi in the mammary gland suggested a hematogenous dissemination of the infection from this organ. Immunologic staining with monoclonal antibody MAb-WF-AF-1, which reacts specifically with Aspergillus hyphae, identified the causative agent in histologic sections of the different affected tissues. The etiologic diagnosis was further supported by the isolation of Aspergillus fumigatus in pure culture from affected tissues and from eight samples of mammary secretions.