How it  works ? 

It works in a simple way now when you hit a neutral animal it can defend itself and attack you

The modified animals are the following cow, pig, rabbit, sheep and octopus

How is the behavior ? 

I say that it is similar to wolves because wolves attack in packs when they are attacked now these animals do the same

How much damage do they do ? 

Well pigs, cows and sheep do 3 damage per hit

the chicken deals 2 damage and the rabbit deals 1 damage

Here some photos:

Here the pigs follow me and attack me

Here the same but with the sheep

And here the chickens began to follow me in a herd for having attacked one of their group

And after that I was fighting a cow to have food

and after that i wanna kill a squid to have ink

and after that i wanna ride with a horse :c but the horse kill me 

and now the goats hate me :c