Ah, now I see why they think he's a quack. He's trying to save animal lives with human methods, probably with techniques like the pulse reading done on Liu Qingyun. Since the dogs have no inner energy like him, they couldn't withstand the treatment.
For a village that treats their dogs as family, it would make sense that they expected a medicine practitioner for humans to do well, even if what they really need is a veterinarian.