Newborn puppies should, if possible, be fed by bottle with a formula manufactured specifically to meet their needs; puppies should not be given whole cow's milk. Cow's milk or other milk products meant for human consumption do not normally contain the nutrients necessary for the healthy development of a puppy.
Puppies generally are not able to digest the lactose in cow's milk, which may result in diarrhea, vomiting or an upset stomach. Commercial puppy formulas are available in pet stores to meet the nutritional demands of puppies much better than whole milk. In addition to being a healthier option, puppy formula is also gentler on puppies' fragile digestive systems.