When referring to animals, blue means grey. Blue is a common color used to describe dog and cats. I am not sure why blue is used and not grey, but sometimes blue indicates a sort of creamy grey that actually has bluish tint to it.
There are bluetick hounds; there are blue/merle great danes, so yes dogs can be "blue." However, I'm not sure if their fur is really blue, or if it's a grey color that looks blue.
I have no personal knowledge of blue-tinted canines, but I figure if they can figure out how to breed certain flowers and fruits/vegetables to create colors, shapes, and sizes which are not native to them, they can do the same for animals. ("They," of course, is the mad scientists and geneticists who spend their time and brilliant minds on these kinds of things.)
I am familiar with the blue tick coon hound and its markings which may make it appear blue. I was not aware that the Chow had a possibility of a blue coat, I have never seen one that particular color.
There is a breed of dog called the Bluetick Coonhound. This dog is typically bred in the southern United States (they originated in Louisiana) where there are many rural areas in which raccoon and other small animals have habitants. The dog has a mottled black and white coat which in light seems to give the impression of a navy blue color. This blue mottling is preferred to lighter ticking probably because they are less visible in the dark (coon hunting takes places often at night). Males weigh 50 to 80 pounds, but there is another breed, the American Blue Gascon Coonhound which is a few inches bigger at the shoulder than the Bluetick Coonhound. Here is a link to them:
I have never seen a chow chow (or any other kind of dog) that was blue. However, I believe that you are correct and that this is actually possible. The reason that I say this is because the American Kennel Club says that it is possible. Here's a quote and a link:
This lion-like, regal breed comes in five colors - red, black, blue, cinnamon and cream - and is known for its blue/black tongue and stilted gait. Their coats can also be either rough or smooth.
Thats interesting (but I'm busy coughing from cinnamon to think right now. Never do the cinnamon challenge! It's bad for you....! )