Knowing what qualities a dog needs to be a success in motion pictures—particularly the ability to register feelings that actual conditions do not warrant—Trimble set out to select a German Shepherd dog for his next canine actor. After extensive research he narrowed the field to three specific dogs, one of them in Germany and two in the U.S. In the autumn of 1920, Trimble found a dog at a kennel in White Plains, New York. Etzel von Oeringen was a male German Shepherd born in 1917. He was trained in Berlin as a police dog and served in the German Red Cross during World War I. At age three the dog was brought to the United States to be sold. Trimble recognized Etzel's potential and persuaded Jane Murfin, a screenwriter for his films, to buy the dog. A new name, Strongheart, was suggested by the publicity department of First National Pictures, which released his first film.