A Tiger's Spirit

People all around the world have always been granted with the opportunity to have two bodies; one in human form, and one in animal. They all represent the animal that they can shapeshift into.
But there are some animal forms that are more dangerous than others, and they also bring great advantage to this world. People around the world have always lived by a rule, that prevents predators from killing smaller animals. It would be inhuman, because the animal forms still feel the same emotions as humans do.
But what happens, when a strange force starts killing all kinds of humans, no matter their form? Will the young tiger save them all, or will he get destroyed with the rest of them?