LOS ANGELES — This weekend’s premiere of “A Dog’s Purpose” has been canceled following the release of a video that appears to show a frightened dog being forced into churning water during production of the film. TMZ published the video Wednesday showing a man struggling to put a dog into a pool of rushing water while the animal fights to stay out. Producer Amblin Entertainment and distributor Universal Pictures haven’t disputed the authenticity of the footage. They say in a joint statement that Universal decided to cancel the premiere because Amblin’s review of the video is ongoing and they don’t want “anything to overshadow this film that celebrates the relationship between animals and humans.”