Two-week-old Reuben McNulty was sitting on a teddy bear ring on the sofa with his mother Amy Litchfield when he was attacked by their pet Staffordshire bull terrier type dog called Dotty.
His father Daniel McNulty dialled 999 when he discovered the scene at their flat in Yaxley, having been outside smoking, Tuesday’s (January 11) hearing in Peterborough was told.
Reuben was taken to hospital in the early hours of November 18, 2018 but died of a severe head injury on December 13, aged five weeks old.
Cambridgeshire’s area coroner Simon Milburn said that Mr McNulty told a 999 call handler that he thought the dog had attacked the baby.
In a police interview summarised by the coroner, Mr McNulty said he “went outside to smoke”.
“He says he went back upstairs to the flat and heard crying,” Mr Milburn said.
“He said on picking (Reuben) up he saw the injuries.”
Simon Newbury, a specialist in veterinary forensics, said there were 23 individual puncture marks.
He said he believed Dotty “saw Reuben as a small prey or squeaky toy”.
Dotty and a second Staffordshire bull terrier type dog called Fizz, both female and aged around seven and nine years of age, were seized by police and later destroyed, the inquest heard.
Mr Milburn said: “It’s clear on any reading of the evidence there had been no previous issues or concerns with either of those dogs.”
He went on: “There’s evidence that both parents were suffering from tiredness understandably as a result of caring for a newborn baby and evidence they had agreements as to who would have a turn at sleep and look after Reuben at various times.
“In the early hours, the explanation given and the explanations I accept, are mother was asleep in the living room.
“She had taken some sleeping tablets.
“Reuben was asleep in the same room in his doughnut, the dogs were either asleep in the same room or on the dog bed.
“Daniel said he had gone out for a cigarette.
“I’ve no reason to dispute that.
“Amy recalls in her police interviews he told her he was going out for a cigarette but unfortunately she fell back asleep and it was when Daniel came back inside a short time later he found Reuben seriously injured.
“I think the best way to characterise that series of events is that it was an unintentional short period of inadvertent inattention which sadly had horrific and tragic consequences.”
Recording a narrative conclusion, he said: “Reuben died as a result of head injuries caused when he was attacked by a dog which was a family pet inside his home address.”
Detective sergeant Emma Compson said police will take no further action against Mr McNulty or Ms Litchfield.
She said the pair had “separated as a result of the trauma”.
Ruth Hinchey, Reuben’s maternal grandmother, said: “I’ve never seen or known Dotty to be aggressive towards anyone.
Social worker Sophie Bradley said Ms Litchfield had been “warned dogs can be unpredictable and can get jealous”.
She said that on visits “both dogs were very friendly and didn’t show signs of aggression”.
She said that, as part of a child protection plan by social services, it was agreed that Mr McNulty and Ms Litchfield “would keep the dogs in the kitchen behind the stairgate, which they already had in place”.
Mr Milburn extended his condolences to the family.