She may be too small to have them, etc.... some dogs need C sections and 18 hours is a long labor. Call your vet.
Brandy, it's a week since you posted this question. How is your dog? Did she give birth?
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them