'A Dog's Purpose' Star Josh Gad 'Shaken and Sad' After Seeing Controversial Video, Investigation Launched

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The fallout continues for the film A Dog's Purpose, after footage of a trainer apparently forcing a struggling dog into a pool surfaced on Wednesday.

Actor Josh Gad, who voices the German Shepherd that was featured in the footage, responded on Twitter to the controversial TMZ video, calling it "disturbing."

"While I do not know all of the details and cannot speak to the level of care and caution that went into this moment (as I was never on set for the making of this film), I am shaken and sad to see any animal put in a situation against its will," Gad wrote in a lengthy post, adding that he has reached out to the production team and studio to ask for an explanation. "I signed on to a film that truly stands out as one of the most beautiful love letters to animals I have ever seen."

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American Humane, an organization that ensures animal safety on movie and television sets, has hired an independent investigator to look into the incident. It has also suspended the safety representative that worked on A Dog's Purpose.

"American Humane has reviewed the video and we are disturbed and concerned by the footage," Mark Stubis, Chief Communications Officer of the American Humane Association, told ET on Thursday. "When the dog showed signs of resistance to jumping in the water, the scene should have been stopped. We are placing the safety representative who was on the set on administrative leave immediately and are bringing in an independent third party to conduct an investigation into this matter."

Meanwhile, Gavin Polone, a producer on the film, told ET that he has seen the controversial video and he is not happy about it. Polone -- an animal activist, a vegan and an animal owner -- also contributes to many animal causes.

"To see an animal put under stress is extremely painful to me," Polone said. "I am not happy with what I saw in the video. No animal should be under stress. The people responsible for this should be held accountable. More investigating should be done on this."

Amblin Entertainment and Universal Pictures have responded to outrage over the video, and said that the dog in question, named Hercules, is "happy and healthy."

"A Dog's Purpose, produced by Amblin Entertainment and distributed by Universal Pictures, is a celebration of the special connection between humans and their dogs," the statement reads. "And in the spirit of this relationship, the Amblin production team followed rigorous protocols to foster an ethical and safe environment for the animals. While we continue to review the circumstances shown in the edited footage, Amblin is confident that great care and concern was shown for the German Shepherd Hercules, as well as for all of the other dogs featured throughout the production of the film."

"There were several days of rehearsal of the water scenes to ensure Hercules was comfortable with all of the stunts," the statement continues. "On the day of the shoot, Hercules did not want to perform the stunt portrayed on the tape so the Amblin production team did not proceed with filming that shot. Hercules is happy and healthy."

PETA (People for the Ethical Treatment of Animals) is now launching a boycott effort of the film, which is based on the 2010 novel written by W. Bruce Cameron. The book chronicles a dog's journey through several lives via reincarnation and how he looks for his purpose through each of his lives.

In a statement to ET, PETA Senior Vice President Lisa Lange said, "PETA is calling on dog lovers to boycott the film in order to send the message that dogs and other animals should be treated humanely, not as movie props."

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Meanwhile, director Lasse Hallstrom commented on the video on Wednesday via Twitter, writing that the animals' safety on set "was of utmost priority."

"We were all committed to providing a loving, respectful and safe environment for all the animals in the film," he tweeted.