There is a woman here named Sylvie Goetz and she is working very hard to save as many perrera dogs as she can. She works directly with the workers at the perrera. However, she has very little control over how the perrera works....she can only help by pulling dogs out before they die. Sylvie's organization is called SOS el Arca. Those of us posting here are really doing so in order to help her, to get the word out to others, so that they can help, too.
I believe it is possible to work with the perrera. There is an non-profit organization in Cancun that works with the Cancun perrera, and now there is even a clinic there, and no dog leaves without first being spayed or neutered. The organization is Centro De Atencion Canina.