Experimental feline herpesvirus infection in the pregnant cat.

Intravenous inoculation of pregnant cats with feline herpesvirus produced minimal illness but resulted in abortion, intrauterine fetal death and congenital fetal infection. Placental lesions included multiple infarcts in the placental labyrinth, thrombosis of maternal vessels in the endometrium and placenta, and multifocal necrosis of the giant-cell trophoblast and endometrial epithelium in the junctional zone of the placenta associated with eosinophilic intranuclear inclusion bodies. The virus was isolated from all the placentas and uteri but from none of the fetuses aborted 6-9 days after maternal intravenous inoculation. Viral antigen was demonstrated in the uterine vessels and in the junctional zone of the placenta at this time. On postinoculation day 26, viral antigen was demonstrated in the chorioallantoic membrane on the fetal side of the placenta and in the liver of a congenitally infected fetus. Although all 4 pregnant cats inoculated intranasally with feline herpesvirus aborted, neither virus, viral antigen nor significant lesions were detected in the uteri, placentas or fetuses. Abortion after intranasal inoculation was interpreted as a nonspecific reaction secondary to the severe, debilitating upper respiratory disease that occurred.