05/03/2012 11:34 am ET

Miley Cyrus Saves Dog Left Outside Walmart

Looks like this is one story that has a happy ending: Miley Cyrus just couldn't say no to a tiny pup abandoned outside of a building. The 19-year-old pop star picked up a small male puppy -- what she thinks is "Rottweiler-beagle mix" -- outside of a Walmart on Tuesday to join the three dogs she already keeps at home, Lila, Floyd and Ziggy.

"He was left in a box in front of Walmart .. I don't understand how people can be so cruel. That's why we named him Happy," Cyrus tweeted.

Cyrus has been photographed often recently on an intense workout regime that involves Pilates classes and jogging with her pups. The dog-lover seems smitten already: "From cardboard to Margelia," she wrote, posting a picture of her new friend.