Garfield: The Movie
(Editor's note: Have you seen the Toy Story films? Well, then you pretty much know the plot. This is a combination of the two, substituting pets for toys.)
Garfield (voice of Bill Murray) finally becomes remorseful over "losing" Odie the dog, and goes out to retrieve him from Happy Chapman (Stephen Tobolowsky). With the help of Persnikitty/Sir Roland (voice of Alan Cumming) and several other dogs and cats from the pound, Odie is rescued. Chapman is arrested for the havoc Garfield creates in the train station. Jon (Breckin Meyer), Liz (Jennifer Love Hewitt), Garfield and Odie live happily ever after.