The puppy will typically wean between six and eight weeks of age, but some may nurse for as long as 10 to 12 weeks. The mother dog will usually start the weaning process by gradually rejecting the puppy's attempts to nurse. She may do this by moving away, turning her head, or snapping at the puppy. The puppy will eventually get the message and stop trying to nurse.
If the mother dog is not around to wean the puppy, you will need to do it yourself. You can start by gradually reducing the number of times the puppy nurses each day. You can also try to distract the puppy with toys or food when it tries to nurse. With time and patience, the puppy will eventually learn not to nurse.