An Australian man who strangled his ex-lover's cat and pelted her parents' home with petrol bombs was on Tuesday jailed for almost 10 years.

Paul Maher (24) began stalking, harassing and threatening his former partner Lynne Forehan in August 2008, shortly after they ended their relationship.

He firebombed her parents' home and, while on bail for breaching a restraining order, broke into Forehan's North Melbourne apartment and strangled her four-year-old cat, Sox, with a telephone cord.

It was a "calculated, callous and terribly cruel act", said judge Felicity Hampel.

Maher, who has a history of mental health problems and drug abuse, also slashed Forehan's couch and clothes and urinated on her bed.

"They were persistent, escalating and very frightening and dangerous," Hampel said of Maher's crimes as she jailed him for nine years and nine months.

Forehan said the cat had been her "baby girl" before the birth of her son and had meant everything to her.

"He knew what she meant to me and when he couldn't get a hold of me and my life, he took her life," she told reporters outside court.

"But now she's in a better place and now I can move on with my son and just be happy."