When Bianca Farrar arrived on her former partner's Melbourne doorstep in January last year armed with two kitchen knives, she told him she just wanted to buy drugs.

But when John Geere asked Farrar to leave the East Bentleigh home he shared with his mother and their dogs, the appearance of his new lover in the hallway sparked a bloody confrontation that left one dog stabbed 23 times and Mr Geere and his new partner treated for knife lacerations in hospital.

The Victorian County Court heard on Thursday that the knives were wrestled off Farrar and she was pinned to the ground before police were called.

Mr Geere's mother later found one of the family dogs, a bull terrier called Snoopy, lying on a blanket in the front bedroom bleeding and barely able to stand.

The injured dog received veterinary treatment and survived the attack, which inflicted 23 stab wounds.

Farrar, 31, of Hampton East, pleaded guilty to aggravated burglary, intentionally causing injury, recklessly causing injury and criminal damage, which is the charge related to stabbing Snoopy.

Sobbing uncontrollably, Farrar, dressed in a black hooded top and blue jeans, buried her face in her hands, as Judge Jane Patrick sentenced her to three years' jail.

In sentencing, Judge Patrick took into account Farrar's psychological conditions which she said reduced some moral culpability.

"I accept your behaviour was irrational and you had no thought-through plan," she said.

But she was satisfied Farrar arrived at the house to confront Mr Geere and his new partner about their relationship.

Judge Patrick described the attack on Snoopy as "very violent, cruel and irrational".

She acknowledged Farrar's long history of chronic drug use, which began at age 11, her chequered education and work as a street prostitute after moving in with a boyfriend from the age of 12.

Farrar, who has already served 204 days in detention, will become eligible for parole in 18 months.