Three decades before ‘Dogman,’ the Buena Vista buddy-cop movie paired Tom Hanks with a French bull mastiff. ‘It was the hardest I’ve ever worked,’ he says.

It all started when Kelly Raisor found Dugger, a six-month-old 90-pound mastiff boxer mix that had been dumped down the road from her house. It took about three days, but Raisor was finally able to ...