The owner of a dog, which attacked a nine-year-old boy and his 27-year-old mother, says the pit bull was actually trying save the boy from drowning.

Police were called to Perricoota Road in the border town of Moama, on the Murray River, about 7pm on Thursday and found the boy with serious dog bite injuries.

A photo of the pit bull. Credit:Twitter/@9NewsMelb

He was rushed to hospital in Echuca before being transferred to Melbourne's Royal Children's Hospital for further treatment. He will undergo surgery to his face and was in a serious condition at the hospital on Friday afternoon.

The woman was allegedly trying to drown her two sons, aged five and nine, and the dog from a neighbouring property was somehow alerted to the commotion and became involved.