An investigation has found that the A Dog's Purpose viral video was fake
http://www.theverge.com/2017/2/4/14508808/investigation-a-dogs-purpose-video-faked-video
The organization explained that the investigation had been carried out by "conducted by a respected animal cruelty expert." It found that experts were present, that the proper safety precautions were taken during the film’s production, and that the dog in question was healthy.share
The statement also explained that the dog, a German Shepherd named Hercules, had been "trained and conditioned” for his scenes, and that while he did show signs of distress, filming had stopped and that he “was not forced to swim in the water at any time." American Humane agreed that the “handling of the dog in the first scene in the video should have been gentler and signs of stress recognized earlier," but explained that the production was adjusted and proceeded without incident.