Mercy Killing? or Cruelty?

whenever i see an animal in pain or in agony i feel the same way, as if they are a part of me, it's like my heart wants to explode ... i want to cry, i want to do something, but i can't, it's beyond my control, how i wish i could help them. Sounds corny but i am stunned whenever i see someone hurting animals... specially dogs, stray... wild... domesticated... or whatever you want to call it... it is still an animal... yes, just an animal for most, but for me... they are an Animal. just an hour ago, in front of our university, a dog was hit and run by a jeep... the poor dog can't move his whole body, so the people drag him to corner... i thought they will aid him or bring him to a vet but because it is just a stray dog, they hit his head and body several times... i feel bad for i can't do anything to help him... they hit him like a pavement that they want to destroy... the helpless dog just cried to death... while the cruel people is smiling while hitting him. My heart almost stopped from beating... a tear almost fell on my cheek, i almost dropped on my knees... all i can do is cursed them! how i wish they will have sufferings like the dog had.