The five-week-old baby, who can only be referred to as MJ, was killed at his NSW Central Coast home in the early hours of July 11, 2021.
MJ's father had purchased the dog called Bully from a breeder advertising American staffordshire terriers about five years earlier on the Gumtree website.
Concerns were raised in the weeks preceding MJ's death that the dog may have been a cross-breed of the more dangerous American pit bull.
On June 7, 2021, Central Coast Council rangers received a report Bully had killed a cocker spaniel from a neighbouring property.
A hole below the fence between the two properties was discovered but there were no witnesses to the attack.
Bully's owners were not home as MJ had been born days earlier.
Rangers visited the properties and after observing Bully were concerned he was an American pit bull.
Ranger Christine Carlin recalled the visit while in the witness stand on the first day of the inquest at a Coroners Court in Lidcombe.
"There were indicators to me, he was possibly pit bull," she said of Bully.
Ms Carlin said the dog had several indicators, including yellow eyes, a liver-coloured nose, white tips on his toes and a tan colour.
Bully had been microchipped in 2016 and his breed recorded as American staffordshire terrier.
But the inquest heard vets are not required to assess breed when recording details for microchipping.
Vets may rely on the breed supplied by the owner.
Following the ranger's concerns, the council sent Bully's owner a notice that it would declare the animal a restricted breed.
This would have imposed control measures on keeping Bully.
Bully's owner had 28 days to respond.
On July 6, 2021, he contacted the council and asked for more time given his partner had given birth. The council granted two more weeks.
Days later, MJ was killed.
MJ's mother had been holding and feeding him in a low-lying rocking chair before both parents fell asleep and Bully attacked.
The vet who later euthanised Bully listed him as a pit bull.
David Kell SC told the court the vet gave this breed based on information from the ranger.
Mr Kell said that six days after the attack, Central Coast Council contacted the vet and asked the breed be changed to American staffordshire terrier.
The vet complied.
The inquest is investigating the circumstances surrounding a number of serious attacks by dogs that led to seven deaths.
The inquest continues.
