Your puppy is changing in so many ways. In fact, the most rapid growth will take place in these first months of his life. His immune system is developing. Bones are growing. Muscles are getting stronger. All of this requires a nutrient-dense diet, formulated to support a medium-breed puppy's rate of development. To make sure your puppy is getting optimal nutrition to protect and maintain health and well-being, here are some key points to keep in mind.
From the time your puppy is weaned until 4 months of age, you should feed your puppy two to three meals a day, with the daily amount based on the guidelines of the food label. After 4 months of age, he should be fed twice a day on a regular schedule. Always have fresh water available.
Research shows that puppies need up to twice as much energy as adult dogs. Dramatic growth at this stage means your puppy requires an energy-rich, nutrient-dense complete and balanced diet. Puppies also require more protein than adult dogs. High-quality animal-based protein will help your puppy create new body tissue.
Not all puppies have the same nutritional needs. Medium-breed puppies actually have slightly higher metabolism rates per pound than large-breed puppies. And your puppy will reach his mature adult weight at about 12 months, sooner than larger breeds that reach adulthood as late as 24 months. Your puppy needs protein, fat, calcium, and phosphorus to support growth and development of bones, muscles, and other tissues. So giving him a food that supports his medium size is the easiest way to help make sure he's getting the right balance of nutrients for his metabolism and growth rate.
Remember, puppies have small stomachs. Make sure his food is nutrient-dense so he'll get a complete and balanced diet even though his stomach can only handle what seems like a small volume of food.
Aside from energy and protein, there are other important nutrients and ingredients vital to your puppy's diet:
These are important building blocks of nutrition. Look for them when you choose dry or canned dog food and when you select treats.
A medium-breed puppy reaches adult weight by about 12 months. You can begin feeding an adult dog food at this time, such as IAMS™ ProActive Health™ Adult MiniChunks. Your dog might not welcome the change at first, but don't worry. You can help ease the transition by gradually introducing the adult food. Try mixing 25% of the new food with 75% of his puppy food, then gradually change the proportions over the next three days until he's eating 100% adult food.

Pregnancy and nursing are not only responsible for many changes in a dog's body, but for changes in her lifestyle as well. If your dog is pregnant or nursing, pay special attention to her changing nutritional needs as she carries, delivers and nurses her puppies.
If you're planning to breed your female dog, it’s important to assess her body condition well in advance of breeding. Because of the physical demands of pregnancy and nursing, a dog with less-than-ideal health can experience problems:
Be sure to feed the proper amounts of a complete and balanced diet. This will support the mother's healthy weight and body condition before breeding and help maintain her health and that of her babies throughout pregnancy and lactation.
The gestation period for dogs is nine weeks. Pregnant dogs gain weight only slightly until about the sixth week, and then gain weight rapidly.
The energy requirements of pregnant dogs are reflected in the pattern of weight gain. Pregnant dogs will need to consume 25% to 50% more than their normal food intake by the end of pregnancy, but energy requirements do not increase until about the sixth week.
The best diet for pregnant and nursing dogs is a high-quality, nutrient-dense pet food formulated for all life stages or for growth. Although puppy diets are generally recommended for pregnant or nursing dogs, large-breed puppy formulas may not be appropriate for this use due to their adjusted energy and mineral content.
Pregnant dogs lose weight after giving birth, but their nutritional needs increase dramatically. Depending on litter size, nursing dogs might need two to three times their normal food requirement to nourish their pups. Be sure your nursing mom has plenty of water so she can generate the milk volume she needs to feed the litter.
To help your nursing dog get enough nutrition, you can try several tactics:

By four to five weeks after birth, most puppies are showing an interest in their mother’s food. Gradually, the puppies will begin eating more solid food and nursing less. At the same time, the nursing mother will usually begin eating less. Most puppies are completely weaned around age 7 to 8 weeks. By this time, the mother's energy requirement is back to normal, and she should be eating her normal pre-pregnancy diet.