Generally dreaming about a dog is good. A dog is loyal, a good friend, and to see a dog in one’s dream signifies loyalty, friendship, protectiveness, all qualities you can find in a dog. As far as you holding back the dog, that could mean many things such as protecting a friend but I would have to get more information…were you walking the dog and pulling on the leash to slow it down…were you holding on to the dog as if to prevent it from doing something you didn’t want it to do.