This article is from the rec.pets.dogs: Breeding Your Dog, posted to rec.pets.dogs newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
You should make sure the bitch is up-to-date on all her vaccinations, medications, and shots before she is bred. She will require supplementary food during the last three weeks or so of pregnancy. In general, puppy food is formulated both for puppies and pregnant or nursing bitches.
She should be under the care of a vet for any related problems. Dogs can have miscarriages. Illnesses, diseases, or infestations that the bitch picks up during her pregnancy can affect the puppies. Difficulties during whelping are entirely possible, and the rule for some breeds. You must be prepared to get her to the vet quickly in an emergency.
There are instances of "mummy puppies" where you have a puppy whose development went awry, but it was not aborted. Instead, it dries and shrivels up, and when born, looks like a mummified puppy, blackened and ready to rot. Overbreeding and inadequate care are usually the causes. It is quite likely that the dam will come down with an infected uterus after such a puppy. "Water puppies" are another type of problem in which the dead puppy appears to have never properly developed a skeleton and appears to be full of gelatin. This seems to be linked to a viral exposure.
Other congenital (but not genetic) defects can include: no anus, cleft palates and hare lips. These conditions require corrective surgery or the puppy will die.
While the bitch is nursing the puppies, she will require about three times the amount of food she normally eats! It is also common for nursing mothers to go out of coat at this time.