Diana Morales with the Calcasieu Animal Services Department said Simoneau used the sword to kill "Puppy," a miniature chow mix that was more than 10 years old.
She said the incident occurred while Simoneau was at an acquaintance's home.
Morales said a person convicted of aggravated cruelty to animals faces a maximum penalty of 10 years in prison and a $25,000 fine.