You may want to reread some of Immanuel Kants work. Especially on whether animals feel pain etc.. I believe you may be just a little mistaken. You can't always apply what was said way back when to modern day.
Way back when was fairly recent, turn of the 19 century.
Any animal with a nervous system feel pain regardless of what he said about it .. (I am unfamiliar with what he said about that).
I can apply that (partial) quote because I feel it applies to the argument and I believe it to be true..
The full quote as it is normally read "He who is cruel to animals becomes hard also in his dealings with men. We can judge the heart of a man by his treatment of animals" - Immanuel Kant
Which I also believe to be true and witness almost everyday.