Puppies can leave their mom when they are at least 8 weeks old, which is the minimum age recommended by breeders, veterinarians, and animal welfare organizations. The optimal age for puppies to leave their mother is typically between 8 and 12 weeks. Many experts lean toward 9 to 10 weeks as an ideal age because puppies at this stage are more mature, confident, fully weaned, and better able to handle the transition to a new home. During the first 8 weeks, puppies receive essential nutrients and antibodies from their mother's milk, and they learn important social and behavioral skills from their mother and littermates. Early separation before 8 weeks can lead to behavioral problems such as fear, poor social skills, and difficulty bonding with humans. Keeping puppies with their litter until about 10 to 12 weeks is increasingly favored to improve socialization and development, but staying longer than 12 weeks is generally not recommended so the puppy has enough time to bond with their new family before their critical socialization period ends around 16 weeks. In summary, while 8 weeks is the minimum age, the best time for puppies to leave their mother and littermates is often considered to be between 9 and 12 weeks old to ensure proper physical, social, and emotional development.