In the wild, showing pain is dangerous. An injured zebra is a target for a lion; a limping wolf is a burden to the pack. Consequently, animals are evolutionary masters of disguise. They possess a "stoic mask" that has allowed their species to survive for millennia.
More specifically, a solid piece of study that combines both is: zoofilia mujeres abotonadas por perros daneses work
: An open-access journal covering pain assessment, stress, and behavioral health. Journal of Veterinary Internal Medicine In the wild, showing pain is dangerous
"Does that thing chime every time you get a notification?" Aris asked. "Constantly," the owner replied. "Why?" Aris explained the behavioral link In the wild