Idiopathic Interstitial Pneumonia Associated with Giant Cells in Aborted Equine Fetus: Case Report

Interstitial pneumonia associated with multinucleated giant cells was noted in an aborted 9-month-old Thoroughbred horse fetus in a routine postmortem examination. The multinucleated giant cells were considered to have originated from interstitial macrophages and blood monocytes that migrated into the bronchiolar lumen and alveolar space. There were no increases in any of the maternal serum titers of antibodies against equine rhinopneumonitis virus, Getah virus, adenovirus or equine arteritis virus, and no pathogenic organisms or metals were detected in the fetal lung tissues. The histopathologic findings of pulmonary lesions offered similarities to “desquamative interstitial pneumonia, ” or “usual interstitial pneumonia” in man.