Unsocialized Older Dogs
By reading this chapter you will understand how critical adequate socialization is, and you will probably recognize older dogs who have not been socialized. In fact, you may have adopted such a dog not realizing that many of her issues are the result of this very thing.
If you recognize that your older dog is inadequately socialized, don't assume that since she's older she can handle things more quickly. You're working against habits that have been reinforced over time — at least a puppy has fewer experiences upon which to base her reactions! An older dog may already be convinced that men are scary, evil creatures, or that young children will hurt her, or that strange dogs should be warned to back off.
A dog's fear and stress levels can range from moderate to severe, and there's the risk that the fear can escalate to aggression. If your dog is so afraid of something that he will bite or attack to avoid it, he needs professional help. Seek it immediately.
These established ways of reacting to perceived threats are a challenge to overcome, but it's certainly worth a try — especially if the dog is basically good-natured. What you'll need to do is identify the things that frighten or stress her, and begin to introduce them in nonthreatening ways. This will take time and ingenuity on your part. Read this chapter several times, and consult with a trainer if you need to. Getting another perspective and having someone's help will benefit everyone.