A coroner is to write to a police force about a nine-year-old boy who was mauled to death by a dog during a Cornish holiday, after his inquest heard the animal had been involved in previous attacks.

Frankie MacRitchie was killed after being left alone in a caravan with the 45kg dog, called Winston, an American bulldog crossed with a staffordshire bull terrier.

The child’s mother, Tawnee Willis, and the dog’s owner, Sadie Totterdell, both from Plymouth, were jailed over the attack, which took place in April 2019.

Cornwall coroner’s court was told the dog had been involved in previous violent incidents.

In 2016 a woman was unable to get out of her car because Winston was baring his teeth and chomping at her car window. She had to ring for help and police spoke to Totterdell about what happened.

In August 2018 a boy playing with the dog was blowing up a balloon when it bit his ear, leaving him needing hospital treatment. The police were not informed of this.

The senior coroner Andrew Cox said he would write a preventing future deaths report to Devon and Cornwall police.

He said: “I want to be very clear, I am not saying that the police did not take the appropriate steps on this occasion. What it seems to me is important is that a robust system is in place so that if there are incidents like this in the future, we can be confident that those dogs that need to be are dealt with.”

The coroner added: “It does raise the question in my mind whether steps could have been taken earlier that may have avoided this tragic outcome. It is manifestly obvious now to us having heard all of the evidence and having learned of the incidents in 2016 and 2018 that there was a risk of this dog attacking Frankie.”

Cox said he accepted Willis did not know about the dog’s history but continued: “The same cannot be said of Ms Totterdell as she must have known of the earlier incidents.”

He said Willis made a “serious error of judgment and a serious mistake” in leaving Frankie alone with the dog, but her negligence was not sufficient to allow him to record a conclusion of unlawful killing.

Instead he gave a narrative conclusion, saying: “While left unsupervised, [Frankie] was attacked by a friend’s dog and suffered fatal injuries.”

Willis apologised in court for her “senseless actions” in leaving her son with the animal. Addressing Frankie’s father, Billy MacRitchie, and grandmother, Pauline Elford, Willis said: “I am truly, truly sorry. I miss him every day and I know they do. From the bottom of my heart I just wish they would get some closure and I hope they will find some peace.”

Willis admitted a charge of child neglect and was jailed for two years. Totterdell was jailed for three years after pleading guilty to owning a dangerously out-of-control dog. The pair had gone out for the evening, leaving dog and child together.