The dog that attacked a dozen people including nine elementary school pupils in Gunma Prefecture earlier this week had not been vaccinated for rabies, the local government said Friday.

The pet owner has admitted that he failed to inoculate the 2-year-old Shikoku that went on a biting spree in Isesaki, Gunma Prefecture, on Wednesday, sending five of the 12 to hospital, although their injuries were not life-threatening.

The owner has a total of seven Shikoku dogs, which are known as a breed of hunting dog, but only three have been registered with the city and there were no records of any having been vaccinated for rabies for nearly 10 years.