Barking Mad

I have a dog who woofs at the sun,
she woofs at sunrise,
as soon as the day's begun.

I have a dog who barks at a star,
she barks at them a lot,
when she sees how many there are.

I have a dog who howls at the moon,
she howls all night,
daybreak can't come too soon!

Now  I bet you're  thinking,
when does she sleep?
It's really quite simple,
It's three dogs I keep!