Final answer:
Pregnant dogs should transition to a growth formula or puppy food by approximately the fifth week of gestation to support the increased nutritional needs of the mother and developing puppies, analogous to the developmental demands experienced in humans during weeks 21-30 of pregnancy.
Step-by-step explanation:
A pregnant dog should begin transitioning to a growth formula or puppy food to support her increased nutritional needs as her pregnancy progresses. Typically, it is suggested to make this transition around the start of the third trimester or roughly in the fifth week of gestation. This change is paramount because the developing puppies require additional nutrients during the later stages of pregnancy, which mirrors the increased demands seen in human pregnancy during the developmental weeks 21-30. For instance, during these developmental weeks in humans, significant growth occurs such as the fetus gaining weight, erythrocyte synthesis by the bone marrow, and the start of myelination processes, all of which require proper nutritional support.
During the final weeks of a dog's pregnancy, the growth formula will provide the necessary proteins, fats, and essential vitamins to ensure the healthy development of the puppies and maintain the mother's condition. This is similar to the colostrum preparation in humans, where high protein nourishment is essential for the imminent arrival of the newborn. High-quality puppy food is typically more calorie-dense and nutrient-rich than adult dog food, which is essential to support the rapid weight gain and fetal development in the litter. Dog owners should transition their pregnant dog's diet slowly over several days to prevent any digestive upset.