Newborn puppies require very regular feeding and should double or even triple in size during those early days. A healthy pup should gain 10 to 15 percent of his body weight a day in the transition from newborn to young pup.
Newborn puppies should be fed every two hours during their first week of life. If you're caring for an orphaned pup, this will mean a lot of nighttime feedings. After one week, you may feed your puppy every three hours for the following three weeks, until he has reached 1 month.
Newborn puppies should only eat puppy milk, which is specially formulated to meet the needs of a growing pup. If you are caring for a newborn puppy, find either powdered or liquid puppy milk replacer. Liquid milk replacer may be served as-is. Powdered milk replacer should be diluted with water per the instructions on the container. Powdered milk replacer that is diluted too much can give your puppy the runs, while not diluting enough can keep puppy constipated.
Just-born pups require such regular feeding because they lack fat stores to use for energy once the food is digested. Regular feeding every two hours ensures the young puppies have enough energy and keeps them healthy. You may need to feed a puppy if the mother rejects him, if she does not produce enough milk to feed all her pups or if your puppy is orphaned.
After one month, your pup can begin eating solid food and should be fully transitioned to solid food by the time he's 7 to 8 weeks old. Start the transition by soaking puppy kibble in warm water or milk replacer until it resembles gruel. Continue to feed your pup some milk replacer, gradually increasing the food and decreasing the milk replacer. Your vet can help you come up with a transition schedule for feeding your puppy.