Northumbria Police said a 30-year-old man arrested in connection with the death of Reggie in Sunderland yesterday has now been released on bail.
Reggie was taken to hospital on Saturday morning after he was bitten by a small terrier-type dog at his home in Falkland Road, in the city, but he died later.
The attack on the newly-born youngster has shocked the quiet residential area where he lived.
Neighbours said he lived with his mother, Maria Blacklin, father, Ryan Young, as well as one of his brothers and a sister.
A relative said the boy’s mother had returned from a family bereavement event in the early hours to find a terrible scene. He wanted to stress that although the baby’s mother was out, the youngster had not been left alone.
The man, who did not want to be named, said the dog - said to be a small terrier-type animal - was usually kept outside, in an outhouse, and was never left alone with the children. He described it as a good natured animal.
He said the family was devastated and wanted to know how the attack could have happened.
Northumbria Police said the dog has been removed from the address and was likely to be destroyed. Officers stressed it no longer posed a danger.
A spokeswoman said: “Police are now in a position to release the name of the baby who died as Reggie Young. Officers are continuing to offer support to Reggie’s family and will continue to do so.
“Extra patrols will remain in the area to offer reassurance to the local community and answer any concerns residents may have.
“A 30-year-old man arrested has been released on police bail.”
Officers were called to the property at 4.15am on Saturday. Bunches of flowers and cuddly toys continue be lain against the front wall of the house in the quiet, tree-lined street.
Some were accompanied with messages of support.
One tribute said: “Our thoughts and prayers are with you at this tragic time. Shine like a bright diamond little one. Beautiful boy gone too soon.”