Animals have been part of Hollywood since the early days of film. But for decades, the safety of animal actors had little or no regulation. Horses and other creatures were regularly pushed to exhaustion or put in dangerous scenes. In the 1940s, the Motion Picture Association of America prohibited cruel and hazardous practices for animal actors. But questions still linger if wild animals should be actors at all. Above, watch a video from TIME.com about the future of animals in Hollywood. Read the March 23, 2012 issue of TIME For Kids to learn more about the use of animals in movies.