As per Wikipedia
"Garfield: The Movie is a 2004 American family comedy film directed by Peter Hewitt inspired by Jim Davis' comic strip of the same name. It stars Breckin Meyer as Jon Arbuckle, Jennifer Love Hewitt as Dr. Liz Wilson, and features Bill Murray as the voice of Garfield. Garfield was created with computer animation, though all other animals were real."
Garfield is a animated Character in the movie. Garfield's friend in the movie is "Odie" a real dog.
How did the movie makers make "Odie" act with an animated character?