You're not over-reacting at all. In a civilised society there is no way that those guys were so hungry they had to do that. There is no excuse in toturing an animal - and I'm sorry it IS torture if the animal doesn't die immediately. What if it had been someone's pet?? Do they not care?

There are ways of reporting things like this. I suggest you email QAWS and let them know what happened and they can pass it on.

Dogs have owners. Cats have staff.