Very difficult to answer! if the world would be perfect we wouldn't need shelters;but it isn't -I know it isn't easy to see animals put down simply because they don't have a home-but zero population growth will take time and no kill shelters are in dire need of funding due to overcrowding. There needs to be an easier method of spaying and neutering-Purdue University is working on it right now. So maybe soon there won't need to be shelters-wouldn't that be great?!!