A Rotorua woman is in Waikato Hospital after being brutally savaged in one of the worst dog attacks ever seen by council officers.

The grandmother is "lucky to be alive", after officers found her more than two hours after she was viciously attacked by an American Staffordshire/Pitbull cross.

Rotorua District Council Animal Control supervisor Kevin Coutts said her injuries were "horrific".

"They were huge, absolutely massive injuries to her right arm. The arm had been eaten right through to the bone in parts."

The woman also broke her leg, but it was not known whether that was during the attack or after it. Coutts said he could not understand how she survived it.

Although it wasn't clear how long the dog had been attacking her for, Coutts said it was at least two hours before animal control officers were called to her Edmund St home on Saturday morning.

He said it was a "family dog", which belonged to the woman's grandson.

"The grandson voluntarily surrendered it and the dog was put down this morning," Coutts said.

While the 65-year-old is now said to be in a stable condition in Waikato Hospital, Coutts said he wondered what it would take for people to "wake up" and realise the breed of dog was dangerous.

"I believe societies have got to decide whether they want these types of dogs among themselves, with their children and their families."

He said statistics "spoke for themselves".

"We know the breed represents 1.53 per cent of all dogs in Rotorua, yet it accounts for some 18 per cent of attacks.

"It's completely disproportionate and people have got to be responsible for the dogs they choose to own."

According to the council, there had been four attacks by American Staffordshire breeds this year alone in Rotorua.

Coutts said the dog was registered and had no recorded incidents against it previously, but it had not been neutered.

Rotorua police were investigating the attack, but no charges had yet been laid.

- © Fairfax NZ News