MNDude, I can see that against smaller animals, but...if you are a 150 lb person against a 500 lb bundle of highly conditioned animal muscle, unless you have a weapon, you are dead meat! Heck, you would be dead meat against a 150 lb leopard. Or even a 75 lb really angry chimp.
Even a really angry 12 lb cat can be more than enough for one of us soft humans.
I'm fairly certain I could beat up a kangaroo. I mean, it'd have to have boxing gloves and shoes, because of the claws, but if you keep it from squaring up and setting it's tail by moving laterally and pepper it with head shots , it'd go down.