Cathy Snyder was, in fact, the owner of the dog in this scene (Riley), along with her husband at the time, David Snyder. She is also an experienced theatrical actor.
Cathy was originally slated to play the Girl in the Cafe, who gets agitated and glances behind her when Jonathan is demonstrating his ability to influence people to David. However, filming dragged on several hours longer than anticipated that night, and Cathy eventually had leave. The part ended up being played by Robert Kersey's girlfriend, Anna Dumas.