Dog that tried to 'save' brother of Murray River drowning victim has been spared.

Buddy, the pitbull cross that tried to ‘save’ the brother of the boy who drowned in the Murray River, will not be put down.

The ‘hero’ dog had been seized by the local council following an order from NSW Police, who now say Buddy was responding to extreme circumstances and was likely acting in “reasonable defence” of the nine-year-old.

On Wednesday, the mother of the two boys took them from their grandparent’s Deniliquin home on Wednesday. She then travelled to the border town of Moama on Thursday afternoon where she allegedly led them to the river, forcing them into the water and trying to drown them.

The older boy managed to escape and run up the riverbank, where police say he was ‘savagely mauled’ by Buddy. Police claimed he also attacked the mother as she tried to drown her youngest son.

In a statement to AAP today, council interim general manager Margot Stork said NSW Police had advised they would not be “seeking an order to destroy this animal.”

"The owner has visited the dog at council's facility and is working with us to ensure compliance with all obligations under the Companion Animals Act," she added.

A GoPetition was launched to spare Buddy's life, with the grandfather of the two boys joining the campaign and pledging to "do everything... to save Buddy."

“I own a similar dog, and I know he was trying to save the boys, it’s their nature when they are raised with kids,” the grandfather wrote on the petition's Facebook page.

He adding that Buddy deserved to back with those who loved him and cared for him, not waiting in a pound for the council to decide his fate.

“Let the ones who his actions affected decide. I have one grandson left, because this brave dog took action as required.”

Buddy's owners also defended his actions on the Facebook page, writing: "Buddy the dog has reacted and attempted to save the boys. In doing so he has bit the eldest boy in his rescue attempts, unfortunately he was unable to save the youngest boy and has also bit the mother".

Buddy's family says he has grown up around children and is a very gentle dog, but would have attempted to help when he saw a child in distress.

"Dogs don't have hands to help like us humans, they have to use their teeth and in doing so it's being portrayed as this dog has attacked the young boy," they wrote.

The five-year-old boy's body was found in the river on Saturday and the nine-year-old remains in a serious condition in Melbourne's Royal Children's Hospital.