Rosie is the Peterson's family pet, she is a fawn bull terrier and she loves to play or run around outside of they're house. She loves to play games with her owner, Opal Peterson and she really wants to play with Oscar
She is Miniature Bull Terrier with fawn with a white diamond shaped mark of her forehead with a red collar with a pink heart tag.
- Rosie was adopted by Opal on her 7th birthday.
- She had an energetic personality, loves to frolic all day, and chases balls around the backyard.
- She was named after her red collar on her neck, giving meaning of the color of a rose.
- Unlike Australian owners, they own Australian shepherds as pets and the Petersons have a bull terrier.
- Rosie is allergic to liver, because it makes her sneeze and have pink eyes. As seen in Oscar's New Girlfriend.