I got this off of this site
http://www.debbiejensen.com/whelping.html
Note # If the Dam is pushing and grunting and crying out in pain
that lasts for over an hour with no visible pup,
you maybe in trouble.
This is when you need to search your gut.
Ask yourself, How do you feel?
Do you feel you are safe or in trouble.
Go by your gut instinct.
Read the Dams signs, her body is talking to you.
She is probably safe if she is napping between contractions,
but if is she becoming exhausted from constant pushing and straining,
if she appears close to collapse you maybe in trouble?
She is telling you something is wrong and a puppy maybe to large to pass thru her pelvis.
If you feel you are in trouble. Call your Vet and get ready to seek help.