|photo from The New York Post 2/2/12|
Stella is performed by canine actor Brigitte, an adorable (is there any other kind?) French Bulldog. According to an New York Post article by Michael Starr, she's a favorite of all the cast.
Brigitte was born in South Dakota, and was going to live with a businessman in Russia. Fortunately, the deal fell through and Good Dog Animals swooped in and scooped her up. Good Dog Animals supplies dogs and cats for TV and movies. And Modern Family called!
Modern Family executive director Christopher Lloyd liked her immediately!
Here's Brigitte aka Stella in a scene from the show: