I had a black lab cross who was such a darling I would sing to him regularly as we drove places. He would absolutely wriggle in delight as I sang "his" song: "A" you're adorable, "B" you're so beautiful....

Best singing dog story I from personal experience:

Berea College, Kentucky; very hot summer evening; non-air-conditioned auditorium; amateur concert inside; small group of us standing on the steps outside, including a rangy old blue tick hound who had been wandering around campus all week, ignoring the no dogs signs on all the buildings.

A choir singing the Hallelujah Chorus; dog suddenly heads into the building; I follow in curiosity; he trotted right up the aisle, up onto the center stage, sat down and proceeded to add his voice to the choir as it reached the grand finale. The audience broke up but the choir finished very nicely. The dog, having done his part, trotted back outside.