The Day No One Was Angry by Toon Tellegen, illustrated by Marc Boutavant
Some of these animals find themselves sunk deep in an existential crisis. Others struggle to manage their rage. Often they find a way to be angry and still live well. Not all of them, though (Hyrax and Aardvark, I mean you).
This really isn't a typical children's book. The elegantly written stories are structured like fables but are complex and layered examinations of the human (or squirrel, or hedgehog) condition. They are also very funny (The Lobster is my favourite).
Buy it for an intelligent child of seven or older. Or buy it for an intelligent adult. It's cheaper than an anger management course.