John Dobbie fractured the 15-week-old child’s skull and left him blind and brain damaged after repeatedly shaking him and striking his head against a surface when he was left in charge of the infant.
A hospital worker who saw the child when Dobbie brought him in said: “I have seen a cot-death baby that looked better than that little boy did.”
Judge Lord Armstrong told Dobbie at the High Court in Edinburgh: “The crime of which you have been convicted is marked by its sheer brutality, by its devastating and catastrophic consequences for your victim who was defenceless.
“A crime of this type could not be more repugnant to a civilised society.”
The judge said that the victim had been extremely vulnerable and had suffered a skull fracture and extensive internal bleeding.
Haemorrhages to the child’s eyes were consistent with extreme and violent shaking of the baby.
“It is difficult to see how your actions, short of murdering him, could have constituted a greater breach of trust,” said the judge.
The force necessary to inflict the skull fracture was equivalent to throwing a baby from a fast-moving car or from an upper window.
Lord Armstrong said of the victim, who is now three years old: “He will be dependent on full-time care for the rest of his life.”
Dobbie, 36, had earlier denied attempting to murder the boy at his home in Overton Mains, Kirkcaldy, in Fife, but was found guilty of the attack which occurred on 5 June, 2011.
The court heard that the child, who cannot be identified for legal reasons, now has cerebral palsy.
He has a limited range of movement and will never be independently mobile.
Notes prepared by a health visitor who saw him days before the attack had described the baby as “bright and alert”.
Dobbie arrived at the Victoria Hospital, in Kirkcaldy, with the child on 5 June 2011.
Staff nurse Jacqueline Keir told Dobbie’s trial: “I initially thought the baby was dead when I first saw it just because it was so lifeless and still – and the colour.”
She said the baby started crying when she moved his hand. “It sounded to me like the baby was in pain,” she said.
The child was transferred to another Fife hospital for specialist paediatric care.
Consultant paediatrician John Morrice said: “For an individual like this who looked so sick I would expect everyone to be available to help out.
“He was not behaving like a normal infant at this point. He was very irritable at times and at other times quite unresponsive.”
The doctor noted bruising on the child’s torso and small, pin prick bruises on other areas such as the top of the head.
He said the priority was to keep the baby alive, to resuscitate and stabilise him. He told the court: “He had life-threatening injuries.”
The child was transferred to the Royal Hospital for Sick Children in Edinburgh for a CT scan and later taken to the Royal Hospital for Sick Children at Yorkhill in Glasgow for neurosurgery.
Detective Constable Kim Stuart said Dingwall-born Dobbie had told him that he had earlier fed the baby and changed his nappy and did not notice any marks on his body.
Dobbie said he had needed to go to the toilet and put the child in an upright position but when he returned found he had slipped on to his side and his head was resting on a plastic phone toy.
Dobbie said the child was crying and he picked him up and noticed a red mark. He said he was shoogling the child.
He noticed the baby’s eyes were rolling back. He took the baby to his mother and she told him to take him to hospital.
Defence solicitor advocate Gordon Martin said the offence appeared to involve “a single loss of control” after he snapped.