In a bitch, urethrastomy was carried out under anesthesia induced by intravenous injection with 0.5 ml/kg of pentobarbital sodium (Nembutal). The animal was laid on its back with the pelvis raised. The skin in front of the pubis was shaved and disinfected. A catheter was inserted into the urethra beyond the bladder. An incision 4-5cm long was made on the median line in an anteroposterior direction 2cm from the edge of the pubis. The urethra was reached by the aid of the catheter introduced into the urethra. The urethral wall was incised, with the mucous membrane grasped by Pean's forceps, and sutured to the skin with silk thread. Button suture was applied to the remainder of the wound on the skin.
Four green monkeys were incoulated intracerebrally with 105.0-106.0TCD50of the low virulent Japanese encephalitis virus, the T37- (S-) strain, but manifested no clinical symptoms. They were held under observation for 14 days and sacrificed for histopathological examination of the central nervous system. As a result, mild changes were noticed in one of two animals inoculated with 106.0TCD50. The other three animals were perfectly free from pathological changes. When sacrificed, all the inoculated momkeys were found to have neutralizing antibody in the blood. It was concluded that the virus tested was much attenuated Japanese encephalitis virus.