Often when we see animals suffering at the hands of others, our first reaction is anger. Frustration is supressed anger. That frustration often comes from us being angry and being unwilling to make changes.
It's been said that anger tells us something is WRONG, and CHANGE is needed. From there, we must examine if something needs changed in the world around us, or if something needs changed within us.
We then get to choose:
Do I hang onto my anger, and make no changes?
Do I make the changes, either by changing the world around me, or by changing myself, that are needed to let my anger go?
Anger is a choice. Change is a choice.