Orphaned puppies require a human to step in and play the "mom role" so they can be healthy and well-adjusted pooches later on in life. At 3 weeks old, their eyes are open and they're starting to move around a bit more. They're still relying on mother's milk, however, so you'll need to get on a regular feeding routine. They're also starting to play a bit more at this point in their lives, making for a fun and exciting time for both you and the pooch.
Keep your house, or at least the area where the puppy is, at approximately 80 degrees.
Make a small nesting box to place the puppy in. This could be a small cardboard box for just one puppy, full of newspaper that is easily disposed of when the pup eliminates.
Place a heating pad or hot water bottle in one corner of the nesting box and under a blanket or towel. In general, the heat source shouldn't take up more than one-half to one-third of the box.
Feed the baby pooch some puppy milk replacement with an eyedropper or nursing bottle every six hours or so. Give the puppy about 5 calories of milk replacement per ounce of his weight.
Mix milk replacement formula with a high-quality puppy food and warm water and place the gruel in a flat saucer that the puppy can easily get to. Put some gruel on your finger and put it close to the pooch's nose, then slowly move your finger toward the saucer for the pooch to follow. He should eagerly start lapping the gruel. Feed the pup at regular six-hour intervals, making sure he's still getting enough formula if he doesn't take to the gruel at first.
Dampen a cotton ball with warm water and gently rub the anal region and the lower abdomen of the pup after every feeding to stimulate elimination. The mother dog licks her pups to do this, but you'll have to improvise with the cotton ball. At 3 weeks the pup may be going potty all on his own, but follow this until you're sure the baby is up to the task.
Spend time nuzzling the pup and also playing with him using your fingers. Puppies naturally start playing at this time, although their coordination is still a little off.