Does your dog growl at strangers? Does he show aggression to people who are unfamiliar? If so, there are some things you can do to help solve the problem. But first, it's important to understand why your dog is acting this way.

Dogs are instinctively aggressive by nature. Aggression came in handy when they lived in the wild - dogs needed aggression to hunt, to defend themselves from other animals, and to defend resources like their food, their den, and their mate.

Over time, selective breeding has significantly lessened and refined this trait. That said, by nature all dogs are still physically capable of causing serious harm. (Just look at his teeth and you know this is true!)

Even though it's instinctive, as dog owners, there's a lot we can do to prevent aggression from rearing its ugly head. And if it does occur (for whatever reason), there are still steps that we can take to recognize and deal with it efficiently.

Aggression in dogs comes in different forms. Aggression towards strangers is one of the most common types. The reason for this type of aggression is nerves. A dog that becomes nervous around unfamiliar people is seeing them as a possible threat. His instinct is to protect himself (and you) from this threat.

Dogs that are nervous around strangers are pretty easy to spot. When someone unfamiliar approaches (a visitor, delivery person, or someone walking down the street) they will usually act one of two ways... Either they will sit completely still, staring hard at the new person, or they'll become agitated. They'll be fidgety, pace back and forth and bark or whine.

The reason a dog acts agressively towards strangers is because he hasn't been exposed to a wide variety of people and places. As a dog owner, it's your job to be sure he learns that strangers aren't a threat. He relies on you to take him on outings where he can meet new people and learn about the world around him.

This is what we call "socialization" - and it's an important part of raising a healthy, stable dog. The best time to start is when he's a puppy, but it should continue throughout your dog's life. Giving him a lot of new experiences helps him become comfortable in new situations. It gives him confidence. The only way this happens is by taking him out in the world and exposing him to new people, places and things.

You can't just bring an adult dog into a crowd of new people and expect him to stay calm and relaxed. Saying "It's okay, Trixie. Settle down" doesn't work. Your dog needs to learn that it's okay on his own. Socializing your dog helps him learn this. You want to expose him to all sorts of people -- small children, teens and old people, kids on skateboards, delivery people in uniforms -- anything that's different from what he's use to seeing at home.

When you start socializing your dog as a puppy, he learns that new experiences are a good thing, instead of something to fear. He'll be much more relaxed and comfortable when he's around strangers.

A fun way to start socializing your new puppy is to sign him up for puppy preschool. These puppy classes are usually held at vet centers or some other indoor, controlled environment. It's a series of classes created specifically for puppies and their owners.

Puppy classes usually have 10-12 new puppies enrolled. It's taught by a qualified dog trainer and one or two assistants. Having more than one instructor is best - it gives you and your puppy more one-on-one time with one of the trainers. Puppy classes usually include information on puppy development and sometimes go into the basic obedience commands like sit and come.

This obedience work is a great way to start your puppy on the road to being a trustworthy and well-behaved dog, but it's really just a "bonus" to the real benefit of puppy classes... which are the play sessions. Several times at each class, the puppies get a chance to run around off-leash and play together. This gives them a chance to learn social skills in a safe, controlled environment. Playing in a group of unfamiliar dogs and people helps them learn how to interact with strange dogs and that they don't have to be afraid of people they don't know.

Yes, puppy classes are the perfect way to start socializing your new dog. But the job doesn't stop there. You'll want to continue taking him to new places so he can experience meeting new people in an unfamiliar environment. Just don't overwhelm him... start off slow, and you'll watch your new puppy blossom into a friendly and confident dog who is always happy to meet someone new!