The dog was chained to a disused vehicle at the side of the property and a female pitbull, believed to be in heat, was also at the property.
While chained up, the dog was easily accessible from the side of the house.
Judge Weir said Matthews had left the property and the toddler was in the care of other children. There was no adult at the house when the attack happened.
The toddler walked out the door to where the dogs were and was set upon by the male pitbull.
The dog was seized by Rotorua District Council's animal control unit and had been kept in the pound until a decision was made about the fate of the dog.
Taryn Tuari, who appeared on behalf of Matthews' lawyer Annette Sykes, said Matthews was a responsible dog owner as the dog had been registered and micro-chipped.
Judge Weir said Matthews expressed regret but showed "limited insight" into her responsibilities as a dog owner.
He said the injuries the toddler suffered were severe and would be with her for some time. The incident had also caused stress and strain within the family. Judge Weir said the dog had been trained as a guard dog to protect Matthews' property.
"One can only hazard a guess as to why you need a dog like this," he said.
"But looking at your previous convictions, they are drug offences."
He said ownership of pitbulls and other menacing breeds was on the rise in Rotorua and he wanted Matthews' sentence to act as a deterrent for other dog owners.
"A deterrent sentence has to be imposed to send a clear message to owners"
Judge Weir also ordered for the dog to be destroyed and Matthews was disqualified from owning a dog for three years.