"how much suffering can you justify by saying that it might save human lives down the road?" - human suffering, or canine suffering? What is the 'exchange rate'

"how much suffering can you justify by saying that it might save human lives down the road?" - human suffering, or canine suffering? What is the 'exchange rate'? And fish suffering? A difficult problem. PS. It's certainly much easier to be the "eventually we would have found other ways"-humanitarian, being a healthy individual :)