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January 2011

Horse: Lung, pneumonia, interstitial, severe, chronic, fibrosing with syncytial cell formation

Detailed Information

Animal: Donkey, advanced age.

Diagnosis: Gross pathology: Lung, fibrosis, diffuse, chronic; Histopathology (PAS reaction, bar = 10µm): Lung, pneumonia, interstitial, severe, chronic, fibrosing with syncytial cell formation

Description: Gross pathology: At necropsy the lung failed to collapse and appeared diffusely firm. The cut surface had reticular thickenings and was diffusely mottled pink to light tan. More than 90% of the lung was affected.

Comments: Only the lung and the heart were submitted for necropsy. Histopathology revealed severe, chronic pneumonia, characterized by interstitial lymphohistiocytic infiltrations accompanied by variable degrees of interstitial fibrosis. Additionally, an active inflammatory component was present multifocally characterized by a suppurative exsudate obliterating alveolar lumina. In addition, numerous syncytial cells containing up to ten nuclei were observed in several alveolar lumina. Special stains for (PAS reaction, Ziehl-Neelsen stain) were negative and no bacterial or parasitic structures were seen in HE stains.

Findings are consistent with a form of interstitial pneumonia recognized in donkeys, associated with gammaherpesviruses asinine herpesvirus 4 (AHV4) and asinine herpesvirus 5 (AHV5).

Picture by: Marie-Charlotte von Deetzen, Department of Veterinary Pathology, Freie Universität Berlin, Germany

Author: Cornelia Holzhausen, Department of Veterinary Pathology, Freie Universität Berlin, Germany