Here's an interesting story I saw this morning.
(If you don't want to read the text, there is a brief video about 3/4's of the way down in the article, showing the dog "singing". )
Now, just to be clear, he doesn't belt out "Old McDonald had a Farm" or anything like that,

but he does have some interesting tones to hear. The first one you hear sounds pretty much like a regular howl, but further into the clip, there are some unusual sounds. Very cool doggie !
Predecessors of a rare dog breed whose howl sounds a bit like a whale’s call are still living in the wild in West Guinea, Indonesia, analysis of DNA has found.
www.cnn.com