FWIW, much of the language of Dog has been sussed out by scientists. There is a lot on line (some sites are better than others) if you want to know what that dog is really saying. Barks mean very little as communication, mostly, but body language is everything. If a dog lies on his back with four feet up, with the head outstretched, that says "You are the top dog here." If a dog puts both front legs out straight, close to the ground, head low and tail end high, that means "Let's play!" Sniffing loudly around the ears means "We can be friends," and often the dog will return that gesture with enthusiasm, sniffing around your ears. A lot of the dog language depends on having a tail, which may be up, down, or wagging. Without a tail, humans really can't say too much to a dog in his language, but these are a few of the "words" that any dog raised among other dogs will understand and accept from a human.
Cheers,
Infrared