Kenjiro Utsumi

Infectious sialodacryoadenitis and rat breeding

The littering rate of female rats was significantly lowered when they had been exposed to sialodacryoadenitis early in pregnancy. Rats of 8 weeks or more of age were highly susceptible to contact infection, showing marked decrease in bodyweight gain, whereas those of 5-6 weeks of age were resistant.

Reproductive disorders in female rats infected with sialodacryoadenitis virus.

Effects of sialodacryoadenitis virus infection on the reproduction of female SHR rats were studied. The oestrous cycle was considerably perturbed in most infected rats, the perturbation was observed initially between Days 0 to 10 post infection and the effect persisted for 6 to 18 days. About half of the foetuses of dams infected on Day 0 of gestation were found dead while only 4% of the foetuses from non-infected dams were found dead. Five or six days after infection on Day 0 of gestation, some infected dams were shown to have metritis, and virus antigen was detectable within the endometrium as well as exudate cells. In dams infected on Day 5 or later of gestation and severely diseased, the offspring showed a low survival rate possibly because of inadequate nursing.