Stopping the killings of animals which can no longer compete

I am writing this petition in an attempt to gain support to stop the killing of animals which are no longer able to compete in races due to sustained injuries. I do not believe that an animal which may have fallen or hurt itself should be killed for the simple reason that it is no longer able to race or compete should have to suffer death because it is not capable of winning or participating in a race. I would appreciate any support in this matter, as i firmly believe that an animal should not be punished in such cruel ways because it is not satisfying the needs of a human/s. I hope others of you will agree with me in this and are willing to sign this petition. Thank you very much.