Have you ever considered fostering?

Over Crowding; When you become a foster for a dog or a cat, that not only ensures that that animal is going to a home but that there is space for another animal at the shelter. Overcrowding is the number one issue that many shelters have; by becoming a foster you help us by providing space for some of our animals. 

Socialization: Most animals that shelters get do come from them being strays. Some animals as strays are not very well socialized towards people; having a foster home allows the animal to settle in a home environment while they begin to learn socialization from people. They can also learn animal to animal socialization from your own pets which can lead to better placement in a home as many other people have a pet already. 

Behavior Issues: Some animals have behavior issues and the benefit to fosterig is that you can give them the one on one care that they would need to help over come those behaiviorlal issues and make them more adoptable.

Age Progression/Senior Animals: Many times shelters get hit with kittens or puppies that are too young to stay in shelter. Kittens and puppies under 8 weeks of age are very susceptible to disease because they are unable to get vaccinated. Senior animals are also very susceptible to disease because their bodies don't fight off the viruses and disease like a younger animal. Shelter life is also very stressful on senior animals, which can make them susceptible for disease.