already has a huge family of pets – but she added one more to the brood with a new Chihuahua on Wednesday.
The heiress adopted the young, male pooch from Pets of Bel Air in Los Angeles just after 1 p.m.
"She loved the puppy, she was all smiles and carried him out of the store in her arms," an onlooker tells PEOPLE. A store employee said Hilton was "so sweet."
The store is the same one where Britney Spears bought
a $3,000 Yorkie puppy less than two weeks ago.
And speaking of celeb purchases: Earlier on Wednesday, rocker Fred Durst and his son came into the store and purchased a Chihuahua as well.
Hilton, who has said she really missed her pets while in jail, also recently bought a new Yorkie named Cinderella, and has another Chihuahua named Tinkerbell, among other pets. (In 2005, she was forced to give up her kinkajou, Baby Luv, because it was considered an exotic species and was illegal to own.)
Reporting by JENNIFER GARCIA