Angus makes mournful howling noice.

[PaulaK]

Joey howls. He has a love/hate relationship with the old rat terrier (Wheezer)next door-they both wait for each other to be out and charge the fence barking. Joey's bark usually morphs into a howl. Annie could care less about the commotion. Neighbors and ourselves joke that our previous dog taught Wheezer the "drill" and now Wheezer has taught Joey. Wheezer really missed our old dog when he became too feeble for the game and was overjoyed when Joey came along and obliged him. Before anyone thinks the rest of the neighborhood hates us - dogs play the game for less than a minute then go about their business.
Paula

[Michael Romanos]

Dogs can talk hatefully ( threatenly) at each other and get the desired response and action. Or it can be a game and a playful conversation.