From a single fertilized cell to a fully formed puppy, the journey of canine pregnancy is nothing short of extraordinary. This complete visual guide walks breeders through every critical stage of in-utero puppy development—from ovulation and blastocyst migration to fetal ossification and whelping readiness. You'll discover how the canine placenta forms, how puppies attach within the uterine horns, and what breeders should know about the zonary placental structure that supports life until birth. With week-by-week developmental insights, anatomical illustrations, and clinical signs to watch for, this post equips responsible breeders with the tools to monitor pregnancy milestones, support maternal health, and prepare for a smooth delivery. Whether you’re new to breeding or refining your protocols, understanding what happens before birth is the foundation of raising strong, thriving litters.