Big breeds such as the Labrador Retriever produces large litters of small puppies and have fewer whelping problems than small breeds such as terriers, which produce smaller litters of large puppies.  Also, breeds with a large head such as Bulldogs usually have more difficulty giving birth than do other breeds.

To prepare for labor, you will need to gather the necessary supplies such as towels, threads for tying off the umbilical cord, and a non-toxic disinfectant for your hands.  Once the mother starts to go into labor, call the vet so he can be prepared for any possible problem.  Do not interfere with the process unless you absolutely have to in order to help the mother if she is having difficulty giving birth.  In this case, she may need some assistance.

The mother should produce a puppy within 2 hours after her water breaks.  The puppies come out at intervals ranging from just a few minutes to 2 hours at a time.  You need to contact a vet if the mother has been straining unproductively for more than half an hour because the puppies may be too large for her to deliver.  The vet may have to perform a cesarean section to where an incision is made in the abdomen so the puppies can be removed by hand.