Your puppy’s nutritional needs will change as he grows into adulthood, but how do you know when your puppy is ready for adult food?
Depending on his breed size, at some point between 12 and 24 months of age, you should reexamine your puppy's nutritional needs and choose the right adult formula. His adult food could depend upon his metabolism (Does he gain weight easily?) and his activity level (Is it low, normal, or high?) These factors can help you find the ideal food for your dog.
The transition to a premium adult formula should begin when your dog approaches adult height and weight. The kind of dog you have will determine the right time to switch. When you do switch to adult formula, follow the same four-day process as you did when introducing your puppy to premium puppy food.
Small-breed dogs tend to mature physically much sooner than large-breed dogs. Follow these guidelines to help you decide when to switch formulas:
As your new puppy quickly matures into adulthood, he needs nutrition appropriate for his 'new' body. That means a high-quality, premium adult formula. Most veterinarians agree that feeding a complete and balanced premium food, such as IAMS™ ProActive Health™ Adult MiniChunks, throughout your dog's adulthood can promote a long and healthy life.
Dogs are as unique as people, but despite their differences, they all need a well-balanced diet for good health. However, dogs of different ages and sizes have different nutritional needs, and this is especially true for puppies. When you factor in developmental needs, ingredients and your puppy’s size and breed, choosing the right food can be difficult.
The energy requirements of a puppy can be nearly twice those of an adult dog. This means that a puppy might not have the stomach capacity to eat enough food to meet his needs unless the food is specially formulated.
When choosing a puppy food, select one that provides a highly digestible, nutrient-dense, 100% complete premium formula for growth. Such high-quality formulas contain the vitamins, minerals, protein, fat and carbohydrates your dog needs for sound and healthy development. With a premium formula, your puppy may have:
Puppies grow fastest during the first six months of life, and because growth rates differ among breed sizes, you need a formula designed to address the needs of your puppy’s breed or size. Feed your puppy this formula based on the recommended amounts for his weight and age until he is an adult.
Although large-breed dogs have bigger bones than medium or small breeds, large-breed puppies do not need more calcium. University studies have shown that:
Overfeeding and weight gain can contribute to developmental bone problems. This makes managing food intake even more critical. Puppies are at greater risk for developmental bone problems if they are overfed.
A formula with reduced fat and calories promotes optimum growth. Controlling the rate of growth to promote normal development is another reason to feed a large-breed diet, such as IAMS™ ProActive Health™ Smart Puppy Large Breed.
Medium-breed puppies have needs between those of large- and small-breed dogs. A medium-breed puppy’s nutritional demands can be satisfied by feeding a 100% complete and balanced formula that features moderate amounts of all the essential vitamins and nutrients, such as IAMS ProActive Health Smart Puppy Original.

Small-breed puppies have unique needs due to their small mouths and small stomachs, as well as the rapid growth spurt they experience when growing to adult size. That’s why it’s important to pack a lot of nutrition and energy into a small amount of food. A poor-quality diet might fill a puppy’s stomach before he can eat enough food to satisfy his nutritional needs. The result can be improper muscle and skeletal development and growth impairment.
IAMS™ puppy foods are formulated to be energy- and nutrient-dense to meet the needs of growing puppies. The IAMS™ formula for small and toy puppy breeds, IAMS™ ProActive Health™ Smart Puppy Small & Toy Breed, has concentrated nutrition for the lifelong health of your small- or toy-breed dog.