Replevin of pet dog

Dear PAO,

I have a pet dog named Blu. Blu was a Christmas gift from my parents. Last year, Lina became my girlfriend. After being in a relationship with Lina for six months, we decided to live together. However, we eventually broke up after I found out she was cheating on me. While I was away, she packed her belongings and also took Blu without my knowledge and consent. She claimed that I gave her Blu as a monthsary gift. However, such an allegation is not true. Blu is like a child to me. How can I recover Blu from my ex-girlfriend?