In our area, we have several animal shelters. I have heard some described as "Open Door" shelters and others as "Limited Access" shelters. What do these terms mean, and what is the difference?
Most communities have at least one "open door" or open admission shelter. This usually means they accept all lost and stray animals, regardless of breed, age or health. Many communities also have limited admission shelters which usually describe themselves as "no kill" because it sounds better.
Most no kill shelters can be no kill because they limit admission. They pick and choose which animals they allow in. They only accept easily adoptable, healthy animals of desirable breeds. They only take in as many as they have space for.
Open door shelters must accept all lost and stray animals, no matter how full they are. No kill does not necessarily mean no kill. A 90% save rate is considered no kill. Some open door shelters have save rates almost this high.
The save rate of community shelters depend largely on how responsible the citizens are with regard to spaying/neutering, breeding, and animal care. Most people who work in shelters do so because they care about animals. They would like to see all animals have loving homes. But someone has to be the bad guy in every community, to clean up the mess made by irresponsible pet owners.
I don't know if it varies from area to area, but I believe that 'Open Door' implies that the shelter accepts any animal, any time of the day in pretty much any condition. Limited access shelters might not take certain kinds of animals, or animals with what appear to be serious health or behavioral concerns. They can also accept certain kinds of animals, but disallow specific breeds.
This is a term that I first became aware of when I discovered Alley Animals, an organization that feeds, rescues and places strays in the Baltimore / Washington area. They came into existence broadly because so many of the shelters and animal hospitals were / are limited access - and generally won't accept known feral animals. The only agency accepting these animals was animal control, which meant an almost certain unpleasant outcome for the animal.
If you've found a stray or injured animal, you definitely want to look for an open door shelter. Lost pets with collars, tattoos, etc would generally be welcome in a limited access facility, but your best bet is to just call them if you can to be sure.
Worth noting, limited access facilities aren't necessarily bad places, and I certainly don't want to portray them as such. They just have very limited facilities, and cope with that by limiting what comes in.