Care of the pregnant bitch

The bitch should continue to have regular, but not strenuous, exercise to help her maintain her muscle tone and not become overweight. If feeding a high quality, premium dog food, a vitamin/minerla supplement is probably not necessary. The premium dog foods today are very good at supplying all the dog needs - that was not necessarily true in the past. Do not oversupplement, as that may be harmful to the developing puppies. Some breeders will add cottage cheese or a cooked egg to the diet on alternate days for extra protein. This is not necessary if a premium dog food is fed but can be done if desired. If you are adding supplements to the diet, get a list of all the ingredients and nutritional labels and take everything to your veterinarian to make sure it is still balanced. Oversupplementing with calcium during pregnancy predisposes the bitch to eclampsia.
She should have been on a premium adult food prior to pregnancy and for the first few weeks of pregnancy. Starting the fourth or fifth week of pregnancy, begin adding a premium performance food or premium puppy food (do NOT use large breed puppy formulas, which are generally lower in protein, fat, and minerals) to her diet. Each week increase the amount of the performance or puppy food and decrease the amount of adult food, so when she is in her final week of pregnancy, she is on all performance/puppy food. Increase the frequency of the daily meals to three by mid pregnancy. She may need to eat small meals every 3-4 hours during the last week of the pregnancy as the puppies continue to take up more room. Remember, most fetal growth occurs in the last two weeks of gestation.
During the last week of pregnancy and the first 3-4 weeks of lactating, she may eat 2-4 times the amount she ate before pregnancy. As long as she is gaining a healthy amount of weight and not becoming obese, she should receive the food. The goal should be to have the bitch weigh the same at weaning as she weighed at breeding providing that this was an ideal weight for her.
If she has external parasites such as fleas or ear mites or internal parasites such as roundworms, discuss treatment options with your veterinarian. It is usually better to treat the mother before the puppies become exposed after birth.
With a few exceptions, (Drugs to Avoid in Pregnant and Nursing Dogs) one should avoid using all medications in pregnant and lactating (nursing) dogs. There may be instances in which a medication not recommended for use during pregnancy may need to be used to save the life of the bitch, even though it may potentially harm the fetuses. Always consult with your veterinarian before administering any drug or supplement to a pregnant or nursing dog.

http://www.peteducation.com/article.cfm?cls=2&cat=1628&articleid=900