In such a world, if we still kept cats as pets, how would we feed them? Would non-industrial, more small-scale farming of animals be able to sustain that, or would exceptions need to be made? I use cats in this example since they, unlike dogs, are carnivores, and they must eat meat to live healthily (unlike us, where a bit of supplementation is enough for entirely vegan diets to be viable).

I'm curious how problems like this would be dealt with in a vegan world. Just let the cats loose on the local rodent and bird population, maybe?