I don't know if a dog could have backed that bear off so quick.

that people with dogs are more likely to be attacked. A couple of months ago a man and his dog were killed together by a bear.

There are black bears in my area and I have run into them in my garden several times. My cats are strictly indoor cats but sometimes they will make a growl like that cat did late at night. It might be another cat outside, or a raccoon, opposum, coyote, bobcat, or Florida panther. Or it might be a bear.