A monster who left a 1-year-old girl needing surgery after a “severe” sex attack, and then tried to blame her mom, has been jailed.

Alan Kusz, 43, commit the vile offense at the 14-month-old infant’s family home in Ayrshire, Scotland, in April 2018, the High Court in Glasgow heard.

The court also heard how Kusz then tried to blame the infant’s mother for the injuries, which a doctor disturbingly described as the “most severe” he had ever seen.

When cops apprehended Kusz, who was often in the company of the child and her mom, he said that he had left the baby and her mother one evening to walk his dog.

He claimed he only returned when he heard the girl “screaming.”

But last month jurors found Kusz guilty of sexually assaulting the girl “to her permanent impairment.” This week, he was sentenced and jailed for 10 years following a hearing at the High Court in Edinburgh.

On passing the sentence, judge Lord Armstrong said Kusz refuses to accept he is guilty — and poses a risk to children in future.

“It is difficult to imagine a more vulnerable victim. You continue to deny any responsibility for the crime of which you have been convicted. Society has an abhorrence of such conduct and it is the responsibility of the court to reflect what. Young and vulnerable children are all entitled to care and protection,” the judge said.

“It is important that those who might be disposed to commit crimes of sexual abuse against children, in the way that you did, understand that they are likely to receive significant custodial penalties once brought to justice. I am satisfied that, in your case, there is no appropriate alternative disposal to one of imprisonment.”

At proceedings earlier this year, the court heard how the “world came crashing down” for the child’s mom after her daughter was left badly injured on April 9, 2018.

The court heard how the infant ended up needing surgery. A pediatrician described her injuries as the “most severe” he had ever seen.

Kusz was arrested and DNA helped to link him to where the attack took place.

The child has reportedly recovered from surgery but doctors say it is “difficult” to say what the future holds for her.

“It is clear that your actions have had a massively negative effect on her ongoing development and that she exhibits the manifest consequences of her resulting physical and emotional trauma,” Lord Armstrong added.

“The sentence which I now impose on you, commensurate with my public duty, is one of a period of imprisonment for 10 years.”

The National Society for the Prevention of Cruelty to Children (NSPCC) of Scotland described the case as “disturbing and horrific.”

“Kusz inflicted appalling injuries on a defenseless baby in his care and clearly poses a serious risk to children,” the organization said after the hearing.

“Babies and young children are completely reliant on the adults who look after them and Kusz abused this trust in the most sickening way imaginable. It is vital he receives treatment behind bars to reduce any threat he poses to children in the future.”