willow said:
would even an Old English Sheepdog bark at strangers?
An Old English Sheepdog would absolutely bark at strangers. They bark at everything else. Seriously, apart from the Basenji, all dogs can bark and most dogs will let you know if there's someone coming up the drive, onto the porch, down the street, into town, etc. I think having a dog as a deterrent is a great idea. My town's had crime waves in the past, but the thieves have never come near my house, which is inhabited (loudly) by a collie mix who weighs around 45lbs and a Yorkshire Terrier who weighs 12lbs. Collies (and herding breeds in general), terriers and the working breeds tend to be the most territorial and protective. Hounds and setters and spaniels tend to be more easy-going about what constitutes their territory and who belongs there, and less effective as watch dogs.
Re: where to get the dog: I always think shelters are good places, but then my experience has been with a good shelter that gives people very good, honest advice about which dog to choose. Some shelters are not very good, and can be less than helpful to people trying to choose a good first dog. If you don't like the vibe in your local shelters, you can try rescue groups - they exist for mixed breeds as well as purebreds. All sources of dogs should be approached with caution and skepticism, especially newspaper ads. Shelters and breeders have some organizations to answer to if you have problems, while the newspaper advertiser can vanish in the night. If they're selling purebred puppies, do research and have a lot of solid questions about their breed, their breeding program, etc. If they're giving away a grown or adolescent dog, consider spending the money to have a trainer evaluate the dog. Personally, I like adopting adult dogs. Skips the puppy mess and medical expenses, and gives you a ready-made companion.