Fetal microscopic lesions in porcine reproductive and respiratory syndrome virus-induced abortion.

Microscopic lesions in four cases of abortion caused by porcine reproductive and respiratory syndrome virus (PRRSV) were characterized by arteritis, myocarditis, and encephalitis. Fetal PRRSV infection was confirmed by virus isolation or immunohistochemistry and serology. Although fetal microscopic lesions in PRRSV abortions are rarely reported, diagnosticians should consider PRRSV when these lesions occur.