A puppy should be at least 7 or 8 weeks old when it is separated from its mother. It is best to gradually wean a puppy over a few weeks, according to the ASPCA.
The process of a puppy becoming independent from its mother is called weaning. During this period, it gradually stops drinking its mothers milk and learns to eat food.
Owners and breeders can start weaning puppies as early as 3 weeks old. To begin weaning, take a puppy away from the mother for short periods of time. When the puppy is alone, show it a bowl of puppy food and water. If the puppy does not eat the food at first, try dipping a finger in the food and holding it up to the puppy. The puppy gradually learns to feed itself from the puppy food and becomes less dependent on its mother for milk. As time progresses, take the puppy away for longer periods of time until it can survive independently from its mother.
If possible, puppies should not be weaned too early, as they can take some time to become independent and learn important social behaviors from their mothers. However, puppies that were orphaned must adapt much earlier. To help an orphaned puppy become independent, the ASPCA recommends feeding the puppy canine milk with a bottle and slowly transitioning to milk in a shallow bowl. Owners can then slowly swap the milk for puppy food.