Answer:
What starts with an 'e' and ends with an 'e' but only has one letter?
What has many keys but can't open a single lock?
Use me to reward good behavior.
I am commonly abbreviated to H
I am full of holes but still holds water.
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk