From the human-centric view of the world perhaps it's not unusual that we would only be able to see Animals in one dimension. And without the layers of complexity that accompany them in reality. So that when they are in physical pain we perceive them to somehow be stoic and uncomplaining about the pain. Or perhaps, we wonder, not feeling the pain at all. The truth is much deeper and more masterful than through simple outward observation such as ethology. They view their physical forms, aka bodies, in a much different way than we do. And without the emotional pain victimization humans perceive accompanies physical pain. Which, it turns out, is inextricably linked with emotion from our viewpoint. To Animals, all sensation is data that informs them about where they are in time and space. This data affords them the opportunity of choosing how to respond vs just reacting. Just imagine such a place of being!

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3438523/