Well, I would say you could make herding people, who can fight such wolves. Of course, this is only a disadvantage for humans, but that's one of the risks of having livestock, isn't it? You could just as well go for the slower-fattening, harder-to-kill wild creeps, but if you choose for livestock, you have to take the consequences too.
And well, I'd say you just put herds of wolves in random places of the map, and they run around on the map, and if they come across a herd, they attack it.
And you could make these wolves attacking other racers by going after their food-gatherers outside of their cities, that go to get food of wild creeps. From the information I believe to have gathered, I think this would work expecially well on orcs, who are made for travelling, and of whcih armies can supply themselves of food whilst on the road. As for elves, I would need more information about their economics system... Dragons, I assume, will have to fly out and eat wild creeps. In that way, you could have the wolves attack the creeps that are edible by the dragons.