“It is not possible to overdose by touching or accidentally inhaling fentanyl, and the same would apply to non-human animals as well,” Leo Beletsky, a professor of law and health sciences at Northeastern University, told The Times on Saturday.

So the dog couldn't have inhaled it then if the story is to be believed because the dog isn't going to intentionally inhale it

Because the drug is poorly absorbed through the stomach, he said, an animal would probably have to ingest the substance through its nose in order to overdose.

Yeah, this is definitely a made up story as others have said. Dog is still lucky it wasn't shot on account of it being a dog near police though.