Tessa is a very vocal little girl, she groans, moans and grunts when she chews her squeak toys. To the point that people I've been talking to on the phone ask who's talking in the background. When she's having a particularly good sleep she whines, yips or snores. But my absolute favorite sound she makes is when she's happy.
When I get up in the morning and take her out Tessa sings to me her appreciation for the start of a new day. By sing I mean howl with various tones and intensities creating her doggy song. When I come home from work and bend down to give her pets she makes these happy little grunts and howls me a song. Some days she howls so hard she falls over backwards. My dad calls her a little coyote. Tessa, when you ask her if she'd like to go work sheep, gets this wild eyed look on her face, bounces to the door and sings her happiness. When she arrives at a location she likes (such as "Uncle Kens"), she will howl her excitement. If you don't seem to be paying attention she'll howl longer, harder and louder.
Based on people's reactions to my singing dog I've discovered this is not normal doggy behavior like wagging a tail. I'm sure there are other dogs out there who howl to their owners, but I've yet to meet them. Does your dog sing to you?