I am trying to think of animals that would make the strongest enemy for humans if they were bred in a laboratory.
My goal is to have an animal that begins by being used in a benign, controlled way, but can go rogue under the right circumstances (which I'm still working at).
I need animals that would, preferably, be naturally loners but would tolerate others of the same kind for some time.
They should be strong and trainable because I need them to originally be used by police/army forces for rescues and crowd control. They would need to be able to drag a fully grown man, climb unstable surfaces, dig...
All that come to my mind are tigers and lions, maybe bears as well but am not sure if they could, with some minor tweaking, be at all usable, or which kind would tolerate it better.
If tigers, lions and/or bears are the best answer then please point that out.
Hybrids could work as well if they could be created in a laboratory only.
P.S. - If I wanted the traditional dog or horse I would use those. I need animals naturally so fierce they would serve as psychological deterrents during crowd control.