After your dog delivers a litter of puppies, your main concerns are her health and the health of the puppies. Ensuring that she is in optimal health, eating right and nursing her puppies, and that the puppies are growing strong, is all you. Keeping the nursing mom away from your male dog or any other unaltered males is necessary to prevent another pregnancy.
No Safety When Nursing
Typically, female dogs become pregnant when mating occurs during her estrus cycle. However, when a female dog is nursing puppies, her body is technically undergoing estrus -- so if a male comes around, she can become pregnant again. For this reason, keeping her away from unaltered male dogs is essential. If the pregnancy was unplanned and you do not intend to breed your dog, this is the time to consider and schedule a spaying procedure. As soon as the puppies are 4 to 5 weeks old and eating solid foods, mama can be spayed.