Answer:
The alphabet goes from A to Z. What goes from Z to A?
While I did live, I food did give, which many one did daily eat. Now being dead, you see they tread me under feet about the street.
What follows a dog wherever it goes?
Though desert men once called me God, today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
It can be white or blue or black, Humped or have a horn. And when it talks it sings its menuets, as it's travelling the depths.
I flow from the Homerβs mouth when he sees doughnuts.