When the film opens, a St. Bernard puppy (later named Beethoven) and some other dogs are stolen from a pet shop by two thieves. Beethoven manages to escape from the thieves and sneaks into the home of the Newton family. The father, George, doesn't want the responsibility of owning a dog, but his wife, Alice, and children convince him. While trying to name the dog, the youngest daughter, Emily, plays a portion of Ludwig van Beethoven's Fifth Symphony and the puppy barks along, thus he is named Beethoven.

Initially, George only focuses on Beethoven's negative aspects: scratching the door, shedding...