The argument is that breeding more animals for the enjoyment of humans is bad, but the existing animals should be given as good of a life as we can. Since rescuing does not directly support the breeders, some vegans are OK with rescuing to give these animals a better life. Some vegans use similar logic to thrift wool sweaters for yarn, when they would not support buying new wool.

Taurine is usually singled or because it is the only nutrient required to meet the AACFO cat food guidelines that can not be readily sourced directly from plants.