The family gathers around the piano to sing a few favorite songs. As musical tones float in harmony from the group, the dog joins in with a howl that just doesn't seem to have a place in "Row, Row Your Boat."
Relax – your dog's howl isn't a comment on the family's singing ability (though your aunt may sound like a thresher machine that's thrown a cog). He probably just wants to show he's part of the family. Howling is one of the few forms of "verbal" communication that dogs possess; others include barking, growling and whining.
In dogs, the howl's purpose is not entirely clear, and it is perhaps one of the least used forms of vocal communication. Its roots go back to dogs' wolf ancestry. Wolves used howling to communicate over long distances. The howl sweeps through different pitches, which helps the sound carry over longer distances than other sounds.
In wolf society, the intent of the howl is to announce to the world, "I'm here!" Wolves use howling to let other pack members know their precise location, if they happen to get separated. A wolf's howl triggers members of the pack to howl back in reply – an acknowledgement that the sent message has been received. Wolves also howl to discourage a rival pack from encroaching on their territory.
So what happens if a lone wolf howls to find its pack but gets a "wrong number" (i.e., the wrong pack answers)? Interestingly, it seems howls are individually recognizable, even to human researchers who track wolves. If a wolf howls and the responding howl doesn't sound familiar, he knows to steer clear of the area.
Wolves in a pack have been known to howl when they wake up in the morning, but the reason for this not entirely clear. Some experts think it may be a way for the pack to reinforce its cohesion, a sort of roll call, except all the wolves are saying "Here!" at once.
Getting back to dogs, these behaviors persist, albeit in a more diluted form, in our family dogs today. Some dogs howl quite a bit, whereas others never howl at all. If you leave, your dog may howl to try to reestablish contact with you. If the howling persists after you've left, it could be a sign of separation anxiety.
But if your dog howls during a song, he's probably just trying to show he's part of the group, not that your singing has gone to the dogs.