6 month old Chow/Lab Mix

Question
Hi Anne,
My husband and I rescued our Chow Mix when she was 3 months old.  I have been obsessed with making sure she is a well-trained dog.  We have been to obedience training where she excelled.  She has no food aggression or toy aggression.  She does well with sitting.  I rollerblade with her and take her for 2 20 minute walks a day.  Recently, she began growling and snarling at neighbors.  I have been working on continuing making her walk by and/or making her sit/stay.  If a person comes up to let her smell them, she growls and jumps away.  She does well with other dogs.  Maybe a little fearful of a lot of big dogs at the dog park where she sometimes sits under the picnic table.  When people come in the house, she is excited and not aggressive.  She does jump on them though...especially when they are more timid toward dogs.  I keep her in a sit/stay until she calms down.  After that, she still tries to jump on the timid ones.  I have been researching, watching the dog whisperer, and trying to keep a good attitude.  (=  I just want to know if I am missing something or what else can I do to calm her aggression/dominance??

Answer
You may not like my initial response, but I suggest you avoid the "Dog Whisperer" and start watching "It's Me or the Dog" instead.  At least Victoria Stillwell seems to know a fearful dog from a dominant one!
A dog that retreats is often fearful.  A dog that is dominantly aggressive will simply stand its ground and expect the intruder to leave, or will stare at, or go forward at the intruder, to make the point.  Aggression toward dogs and aggression toward people are not the same.  Some dogs that are very aggressive with dogs really like people, and some that like people are very aggressive with dogs - so liking other dogs is not a predictor that the dog will like people, and vice versa.
Some dogs, at around age 5-6 months, exhibit a fear stage.  Instead of forcing the dog to sit, which may be making her even more anxious (after all, now she's trapped), I would have taken out some roast beef and started feeding her as the people appeared, and stopped feeding her as the people walked away, and I would not force people on her.  We call that "open bar - closed bar", and it tends to make the dog change their emotional response to the appearance of strangers to one that's more positive, and less fear-inducing.  I would have anyone who wants to interact with her stand still, body turned to the side (exposing one's flank is a sign to dogs that you mean no harm) not stare at the dog, and not make any overtures with their hands.  I let the fearful dog decide whether to investigate the person, and do it at their own pace.  Often, once the dog builds up the confidence to go and sniff the person (which the fearful dog generally doesn't do if the person approaches frontally and stares), they  will accept a treat dropped on the floor, but with the dog that growls, take good care not to go too fast, as you don't want to have her reach the bite threshold and take a nip out of fear.  Dogs learn contextually (in pictures, if you will), so she may have learned that she is always safe inside the house.  The people who enter are considered safe because nothing bad has ever happened to her in that context, from puppy hood.  But, outdoors, if she was not extremely well socialized to people approaching (or if the fear period thing is the issue), she may not be as secure, hence the desire to warn and leave the area.  Also, you do need to be prepared for the fact that Chows and Chow mixes often exhibit wariness or dislike of strangers.  They are often considered one person dogs, and if you ask any groomer, or vet tech, they will tell you that extra care is taken with such dogs in the salon or the clinic.  Of course, the same is true of many other breeds as well, and it's also true that the stereotypes don't always hold true - not all Golden Retrievers are friendly, for example.  And, certainly, not all Chows are aloof with strangers.  
Another possibility you may consider is that she has a vision problem, but that is easily ruled out by a visit to the vet.  Any time a behavior starts suddenly, it's not a bad idea to check the dog out medically.
It is certainly good to train your dog to focus her attention on you, but I like to use hands off training, especially with fearful or aggressive dogs.  www.clickerlessons.com has free instructions, and other information that may be useful can be found at "Holly's Den" - the trainer who constructed that site is now retired, but left it up for all to see, and there's good info there on a variety of things.