Dog behavior in the shelter environment

Many dogs in the shelter environment feel stressed. While some dogs may be friendly and outgoing, you're also likely to see many dogs exhibiting some of their worst traits. Stress and anxiety often brings out the worst in any of us and the same is true with dogs. In many cases a dog doesn't start to relax in a shelter until he's been there at least three days. 
Some shelters have taken steps to try to overcome this problem. 

Some shelters also have volunteers who come in specifically to pet and play with the dogs. This also helps to relax the dogs and relieve some of their stress. They can take the dogs for walks outside so the dogs aren't cooped up in the kennel runs all the time. 

It's important to remember when you're at the shelter or rescue that some of the dogs you're meeting might have already been through a lot. For example, dogs have often lost their home and family, for whatever reason. They are enduring the current stress of living in a kennel situation which is new for many of the dogs. Some of the dogs may have been neglected or worse. Plus, many dogs in shelters have never received any kind of training. They could have been turned in to the shelter because they were considered to be “problem” dogs. All of these things can bring out the worst in a dog. 

Dogs are born with a predisposition to certain behaviors and actions which makes up part of their temperament. However, their temperament is also affected by their environment throughout their life, especially during their early life. And these are ex strays, their lives wasn't a picnic...