A dog who reportedly 'attacked' an Australian woman will not be put down, as his owners had feared, after police determined that the animal had been acting to defend the woman's son.

More than 50,000 people had signed a petition to spare the dog's life following the incident in Moama, New South Wales. The woman, understood to be a crystal meth addict, had allegedly brought her two sons, aged 5 and 9, to the Murray River last Thursday in order to drown them.

According to local reports, the woman had first ordered the older boy into the water, but he escaped and ran up the river bank - at which point he was bitten by the dog, a pitbull named Buddy. The dog then attacked the mother.

The younger boy's body was later recovered from the water following a police search. The mother is expected to be charged with murder and attempted murder.