Vegan

Very few western vegans want to imagine that, in a vegan world, domestic pets would go the way of domestic livestock. But a world that takes animal rights seriously is not a world that uses animals for human pleasure, whether that pleasure comes from food or companionship. Vegans aren't "pet owners" because vegans don't see animals as things to be owned.

Which is all to say, healthy plant based pet food may or may not be possible, but either way it's not going to be vegan.