Uh, the fantasy world your dad described is not the real world. Cows are one thing, they are too big to lose except perhaps in India, but do you have any idea what environmental damage is being done by feral pigs that were "let free to eat for the day' and never came back? If you want to domesticate an animal to work for you, then you take responsibility for it and all it does, plain and simple. Eventually we will use DNA and chipping to charge people for the costs of their "companion" animals, which are only now becoming apparent.

It should not be too surprising what apex predators like cats (we make them tiny, but they are at the top of the food chain nonetheless) can do to ecosystems if crazy people (us) confuse them with cuddly toys and breed and feed them without control.