Normally, a mother dog takes care of all her puppies' needs for the first month of their life. But sometimes it is necessary to feed one or more puppies in a litter with formula. Never use formula made for human babies in these instances. Human baby formula can make puppies sick.
Human vs. Canine
Significant differences exist between formula made for human babies and puppy formula. Human formula made with cow's milk contains lactose. Puppies are unable to digest this and it can give them diarrhea. Diarrhea in puppies can quickly lead to dehydration and death.
When to Supplement
Small or weak puppies in a litter may nurse, but still need extra formula to help strengthen them. Sometimes a very small puppy has difficulty getting to a nipple if he's pushed away by larger littermates. Very large litters may need to be supplemented with additional feedings if the mother dog can't produce enough milk. You may need to supplement the puppies from a mother who rejects them or is ill, or a litter that is orphaned.
Consult a veterinarian for the best formula for your puppy. There are excellent commercial puppy milk replacements available. These are usually powders that can be mixed with water and refrigerated for 24 hours. Your vet may be able to provide you with a prepared formula, or you can order it online.
In a pinch, you can make a formula for short-term feeding until you can get a puppy formula. Mix 1 cup of whole milk, 1 teaspoon regular vegetable oil, 1 drop of liquid multivitamin for infants, and 2 egg yolks. Blend well, and store in the refrigerator for up to 24 hours, then discard any unused portion.
How to Feed Formula
Warm formula to room temperature before feeding. Be sure it's not too hot. Don't feed newborn puppies with an eyedropper. If the puppy doesn't swallow, he could inhale, or aspirate the formula and develop pneumonia. Ask your vet to teach you to tube feed or sponge feed the puppy. An older puppy can nurse from small bottles designed for squirrels, available online.
Feed newborn puppies every two hours around the clock. Puppies should gain weight daily, sometimes doubling their weight weekly, depending on the breed. Use a digital scale to weigh your puppies daily and keep a log of their growth. As puppies grow, you can extend feeding time to three- and then four-hour intervals. Begin the weaning process around 4 weeks of age, starting puppies on warm oatmeal or rice baby cereal mixed with puppy formula, gradually transitioning over a week or two to puppy food soaked in hot water until it's mush.