Updated 6:29 PM with statement from Amblin (below): Gavin Polone, the producer of A Dog’s Purpose who is also an animal rights activist and has actually written publicly about making sure animals are treated properly in the entertainment field, told Deadline today that he was “horrified” about what happened in a second unit shoot on the set of his upcoming Universal film. PETA is asking moviegoers to boycott A Dog’s Purpose (read its statement below) after video emerged…