"There are a number of reasons dogs bark. The most common include:
- Alerting behavior, such as when a stranger is at the front door.
- To show excitement, like you would see during an active play session.
- To communicate with you when he wants something, as in, "Let's go outside!"
- To communicate with other dogs when he wants to say hello or something else.
- Separation behavior, such as when dogs bark, bark, bark when their owners are gone.
Some herding breeds, like the Shetland sheepdog, will also bark when something is moving. This can be caused by excitement or a desire to herd the object. You've mentioned several situations that sound like moving objects are an issue, including cars, falling leaves, vacuum cleaners, brooms, snow, and other dogs. "
More at: http://www.pawnation.com/2010/03/17/ask-the-akc-animal-behaviorist-help-my-dog-wont-stop-barking/?icid=main|htmlws-main-n|dl6|link3|http%3A%2F%2Fwww.pawnation.com%2F2010%2F03%2F17%2Fask-the-akc-animal-behaviorist-help-my-dog-wont-stop-barking%2F
More training tips for barking and growling at strangers:
“He may be protecting you or his territory, or he could be fearful of new people. How do your visitors act when they meet Devon? Sometimes, when a dog begins to bark or growl, the visitor goes out of his or her way to make friends with your dog. Some people will reach to pet the dog and others start talking in gushy baby talk. This is weird to the dog.”
My new foster dog.
I drove to the next town for the third day in a row. That is very unusual for me. It was SPCA's Adoption Day, but I wasn't taking my foster cats. I was going to pick up a dog. His name is Sparky, and he is a Long Coat Chihuahua. He looks more like a little fox, so I would have called him "Foxy".
This is his story:
Five years ago, when he was a year old, his left eye got hurt, and was hanging out of it's socket. His 'hoomans' wouldn't/couldn't take him to the vet so he was turned over to our SPCA. By the time they got him, it was too late to save the eye, but he was adopted by a family with a little boy. He slept with the little boy, and everything was great until a new baby came along.
Once the baby got up on his hind feet, Sparky started nipping at him. The baby was fostered and the family were waiting to adopt him. If Social Services had got wind of this, even if the family had the time, knowledge and inclination to re-train Sparky, it would be all over.
My SPCA boss has been taking care of Sparky for two weeks, as well as her fosters and personal animals. But she is kind of snowed under, as her parents are ill in separate hospitals, and her husband is having chemo at a third. Sparky was scared of her larger dogs, so she would have to take him out separately, and he wouldn't tend to business unless she stayed with him. Then he wouldn't come back in, so she would have to go get him, and carry him back indoors. So I am trying to take a little load of her.
He had never been to Adoption day, so he was upset and confused, but he sat on my lap and we got to know each other. I took him for a walk around Petco, and when he got to the giant bags of dog food on the bottom shelf, I could see his little brain saying "This isn't such a bad place after all!"
Now he is sleeping beside me, and seems content, so it is a good day.