[wizofaus]

The "mirror test" isn't a bad place to start, and there are definitely animals that pass it that aren't human. But trying convincing dog-lovers that their dogs aren't sentient... (Personally, I'm not sure - but I do suspect they at least have some subjective experience of the world, they "feel" emotions, and are aware of the boundary between themselves and the rest of the world. Apparently they've even tried to measure sentience in dogs via MRI scans etc., and supposedly couldn't distinguish them from humans).