It is understood the boy and his father were packing up about 12.40pm from a few days camping in the bush and were about to make their way back to Turangi.
"There's some thought that the dog had been spooked and it jumped up on the boy and bit him on and around the lips," Graeme Harvey, spokesman for Taupo Hospital, said.
"According to the father, they didn't know the dog or the owner of the dog. But they've had a discussion and the owner's very distraught and has advised that he would be putting the dog down."
The boy was treated at the scene and given pain relief by St John staff from Turangi then was taken to Taupo Hospital where his injuries were dressed.
There the decision was made to fly him to Waikato Hospital by Youthtown Trust Rescue Helicopter so he could be seen by a paediatrician and surgical team.
Mr Harvey said the boy would most likely need reconstructive surgery to repair the damage to his lips and mouth.
"The injury was quite localised to the mouth area, so it wasn't full facial ... but it was very much something that was needed to be seen by the surgical team at Waikato."
Last week, a 13-year-old Te Puke girl was bitten on the top of her arm by a neighbour's pitbull. Although her injuries were not serious, the girl was traumatised by the attack. She was now startled and frightened by the sound of the family's own dog barking, her mother said.
The pitbull was destroyed.
Nearly 12,000 people suffered dog bite injuries last year, including more than 1700 children aged under 10 - many of whom will be left with scars.
ACC claim statistics showed the 11,708 claims made by dog-attack victims in 2011 were at a cost of $2.4 million.
Of those claims, 872 were for children under the age of five, 891 for 5-9-year-olds (the highest for any age bracket) and 705 for 10-14-year-olds - similar figures to 2010.
The number of attacks requiring medical attention has increased since 2003 when 8677 people were attacked.
Recent dog attacks in New Zealand
* In January 2012, 3-year-old Rikiau West-Pakuria spent weeks in an induced coma after his aunt's dog bit him in the throat.
*On Christmas Day 2011, a 15-month-old Ozyris Beeching was bitten in the face by a dog in Edgecumbe.
*In July 2011, 4-year-old Ben Oliver was attacked by a bull mastiff-great dane in Titirangi, puncturing his cheek, lip and chin.
* In 2011 an 18-month-old girl received significant injuries to her face and stomach after being attacked at her Porirua home by a pitbull-Staffordshire.
* In 2011 a 9-year-old girl received deep cuts to her head and arm after being attacked by an American bulldog in Rotorua.
* In August 2009 Maggie Christensen was mauled by eight pig dogs, requiring her to have extensive and painful surgery.
