Demand an End to all animal cruelty and for a stupid thing like "they're too slow!" Who has they say as to what speed they should run?

I rad where 6000 Greyhounds were put down because they were too "slow!" In whose opinion, may I ask? I surely do not have the say as to how fast a dog should run nor does anyone else. This is so ludicrous, it is sickening. Animals have rights just as humans and the abuse and cruelty have got to stop!!