Answer:
In my life I must bare, my bloodline I must share. What am I?
Curtail me thrice I am a youth; behead me once a snake; complete I'm often used in truth when certain steps you'd take.
What is so delicate that saying its name breaks it?
What begins with T ends with T and has T in it?
I am a box who holds keys but not locks. With the right combination I may unlock your soul
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