Animals gone beserk
Everywhere you look animals do fight but why do they do it? Research shows that most animals fight because they don't want tresspassers in there territory. I think its because most animals just love to fight. If you've ever been to a circus, you can see that the people there abuse animals and hardly feed them. Animal abuse is bad and you can get arrested for doing bad stuff to animals. My point is, is that some animals today hate us humans, and i can't say i blame them. An animal is aggrivated by anything that may agitate it or even look at it.
Anger
Just like humans animals can get mad when pushed to their limits. If you've ever been mad then you know that animlas can get mad by your actions. The animal brain is not very different from a humans brain. It can make animal choose what action it does or doesn't. If you have ever seen dogs barking or howling, then there either mad or lonely.