Lee Michael McGonnell, of Beecham Street, Morecambe, assaulted the woman in Lancaster on Christmas Day, Preston Magistrates’ heard.
On April 2 he damaged her door causing £800 damage.
The bench said he had similar convictions, that it was an “ongoing campaign” and his victims were “vulnerable”.
McGonnell admits criminal damage and assault.
The 29-year-old defendant also admits a charge of causing the woman to fear violence by making the threats about her dog while she was walking it, and by banging on her fence and threatening to wreck her garden.
The court has imposed a restraining order to protect his victim.