Hi there.
I get ya'll point of not hurting Onbu. But try to look at it from the other side - the fictional world is heavily inbued with these spores and disease. Onbu as well as people in this world are literally bond to die. So, as Zaru noted, if you look at the bigger picture - if in order to save Onbu you have to make sure your population can get through any disease then heal, antidote and pet Onbu to make him feel good, why wouldnt i?
So actually this co-existance is much more complex and there might be times where it's necessary things in order to survive.
I just finished the game on the veteran level with extra steps and had to use these blood extractors in the mid-game stage. And i don't mind it, Onbu was kept in perfect health whole game, was wagging tail a lot. Even tho we had some rough times in the beginnings
