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.
 
 As dogs age, changes occur in the way their bodies function, so it makes sense that what they eat also might need to change. The following list of health issues might be more common in aging pets.
Decreased Immune System Function
Throughout a dog’s life, a process called peroxidation occurs. Peroxidation is a normal process that the body uses to destroy cells that outlive their usefulness and to kill germs, parasites, etc. This process, however, also can destroy or damage healthy cells. As your dog ages, the damage caused by peroxidation accumulates, which, in turn, increases the risk of certain problems, such as infections.
 
Antioxidants are naturally occurring nutrients that help maintain overall health by neutralizing the peroxidation process of cellular molecules. Some antioxidants, such as vitamin E, beta-carotene, and lutein, are naturally occurring nutrients.
 
Recent research sponsored by The IAMS™ Company found that dogs fed a diet rich in antioxidants such as vitamin E, lutein, or beta-carotene had improved immune responses and vaccine recognition. This might be especially important in senior dog care; IAMS research has found that as dogs age, immune responses can decrease.
More Frequent Intestinal Problems
Older dogs might have higher numbers of unfavorable bacteria and lower numbers of beneficial bacteria in their intestines, which can result in clinical signs of gastrointestinal problems (e.g., diarrhea).
 
Feeding a diet containing fructooligosaccharides (FOS), a unique fiber source that helps nutritionally maintain healthy intestinal bacterial populations, promotes growth of beneficial bacteria. Beet pulp, a moderably fermentable fiber source, also helps maintain intestinal health by providing energy for the cells lining the intestine and promoting small, firm stools.
Different dogs show signs of aging at different times, and much of this variation is associated with size. Larger dogs generally appear 'old' sooner than smaller dogs. The table below lists the age at which various groups of dogs should be transitioned to senior foods, such as IAMS™ ProActive Health™ Senior Plus.
| Weight Range | Age to Begin Transition | 
|---|---|
| More than 90 lbs | 5 years | 
| 51 to 90 lbs | 6 years | 
| 21 to 50 lbs | 7 years | 
| Up to 20 lbs | 7 years |