It can pose a threat to forests because they can wonder off into the forest and then (depending on the animal) can potentially pose threats to the wildlife and the plant life too. also the animals that go in there they can get harmed and eaten my other animals so those animals that eat them could start to be accustomed to the animals that wonder on there and start to go to were the livestock is originally from and that can also pose a threat to the livestock as well...hope I helped
