Since literally ever. What do you think wild dogs and wolves ate before humans domesticated them? And foxes (same family) are still widely known for running off with chickens.
Why thank you :) Although vegan could be an alternative, dogs and cats do have carnivore teeth, they are fine eating small rodents and for dogs even some bigger animals.
Ever hear of cats Mousing or hunting birds or other small animals? And dogs used to travel in packs and hunt and kill Deer and other animals before humans tamed them and dogs can and will eat raw Eggs especially if you own chickens and they can steal them from the coop, both Dogs and Cats will also kills chickens, I know I've had both kill chickens before. Dogs and cats may have not eaten Cows and dairy in the past very much but then again before Dog food came around in the last few decades they were largely given table scraps