The aunt of a partially-sighted boy who was mauled by a dog said her four-year-old nephew was savaged "like he was a doll".
Thomas was attacked while out walking with his father
Thomas Miles was attacked by the animal, thought to be a Rhodesian Ridgeback, outside a house in Holywell, Flintshire on Tuesday evening.
His father Steven, who is also partially-sighted, and an off-duty policeman, were also injured.
The dog was later destroyed and tests are underway to confirm its breed.
Police were called at 1920 BST on Tuesday after reports Thomas had been attacked on the Tan y Felin estate in Greenfield.
His aunt, Caroline Miles, said: "They were walking back from the chip shop and my brother said he saw a dog walking over to them which he thought was a Labrador because he can't see very well.
"He thought the dog was after his chips but then it grabbed Thomas and caught him on the inside of his right leg.
"It picked him up and ran down the street with him, Thomas's head was bashed on the pavement.
"Steven said he was punching, kicking and trying to gouge the dog's eyes.
"The dog grabbed him by the shoulders and he somehow managed to get him off Thomas and picked him up and ran up the street.
"Steven said the dog was running behind jumping up at him."
She said Mr Miles, a single father, ran to the nearest house where off-duty police officer Tony Jones, 38, opened the door and let them in.
Thomas was attacked by the dog while walking home with his father
She said: "That policeman saved Thomas's life. It could have been anyone at the door and he just let them in and then went out to deal with the dog which attacked him.
"We are so grateful to him."
Thomas was taken to Glan Clwyd Hospital in Bodelwyddan by ambulance where he underwent emergency surgery.
He was released from hospital on Thursday, but his family have been told he may need plastic surgery.
Miss Miles said they were concerned how the experience would affect him.
"We're all worried now that with his eyesight he'll be too scared to go out. People need to learn to keep their animals under control," she added.
North Wales Police are investigating the incident but say preliminary inquiries suggest the dog was not of a breed banned under the 1991 Dangerous Dogs Act.