The best days to palpate (feel for) puppies are about day 28 to day35 of the pregnancy. Usually it is best to count from the last breedingday as most dogs actually ovulate shortly before they quit standing forthe male. X-rays can confirm pregnancy after 45 days. Sometimes it is worthwhileto take X-rays to get an idea of the number of puppies -- usually we dothis only if we suspect that there are problems or if the bitch has hadtrouble delivering puppies previously.
It is best to gradually change the bitch to a puppy formula dog food at about 35 days of the pregnancy (take about a week to slowly make thechange, mixing in small amounts of puppy food with normal food the firstday and gradually increasing the amount). Most bitches require about 1.5times the normal amount of food for their maintenance at the time of birth.As the puppies grow, she may require as much as 3 times normal amountsof food to support lactation. You should continue to keep her on a puppyformula until the puppies are weaned.
Do not supplement calcium during the pregnancy. This seems to lead toproblems with uterine inertia, increasing the probability that a cesareansection may be necessary. It may also contribute to the frequency of seizureproblems associated with low blood calcium levels during lactation (milktetany).
Know your veterinarian's emergency procedures before the delivery. Ifyour vet refers emergencies to an emergency clinic, make sure you knowwhere it is and how to call if you need help. If your veterinary hospitalstaff covers its own emergencies it is still important to know the procedurefor contacting someone before the need arises. Ask about this. Write thephone numbers down where you can easily find them.
Your vet is likely to have some references that cover construction ofbreeding boxes to protect the puppies. I can not remember the titles ofthe ones we have, offhand --- they are from Purina, though. Providing asafe environment for the puppies is important. More puppies die from hypothermiathan anything else, probably. Making arrangements to ensure the puppieswill stay warm is important. On the other hand, you can't just warm upa whole room to 80 degrees because Mom has to be willing to stay with thepuppies. The puppy heating pads are nice and sometimes other arrangementscan be made to safely supply a warm spot for the puppies without makingit too hot for the mother.
Breeders are a good source of information in most cases and it wouldbe a good idea to continue to try to talk to yours. They often have practicalinformation that vets don't have experience with.