Puppy systems seem to be simulated by sucking .
They should have a bile movement at least every other time .You can use a very warm wet towel or cotton ball and stroke the puppy's rectum until he relives himself .Keep the pup warm while feeding by wrapping him in an old washcloth or towel . I wrap the puppy as you would a human baby . You can also wrap the bottle with a paper towel or kleenex to keep it warm. I also keep a cup of very warm water near by and when I burp the pup I set the bottle in the warm water to keep it warm. I use a four tablespoon puppy bottle you can use the shorter or longer tapered nipple depending on your puppys preferrence and what breed you are feeding.