Killing Healthy Animals?

I was deeply concerned, when reading this article about British animal protection association RSPCA. It says that the RSPCA kills perfectly healthy animals and rather pursue humans whom they think abuses animals than helping the animals. One story is about five perfectly healthy cats put to death. The RSPCA does respond, but I am still not convinced. I do think it is important to bring animal abusers to justice, but the most important thing is to take care of the abused or abandoned animals. Things can be done in a better way.