There's vegetarian dog food. And this says:
If I were one of the animals that has like a 90% chance of being attacked and killed by a preditor, I'd think life wasn't worth it and kill myself painlessly if I could. Unfortunately, animals can't so I predict that one day humans will do something about it. Killing the preditors wouldn't be a popular choice these days, so I thought of the carnivore to herbivore idea.
Hopefully there's a conservation benefit and a safety-for-humans benefit because I don't think people care as much about preventing countless cases of horrible suffering than those issues.