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 | 
 
 Dogs hit maturity around 7 years of age (5 years for larger dogs). It's not uncommon for them to live as long as 15 years. As your pet enters his golden years, his activity level might slow down and common conditions such as arthritis, diabetes, and kidney disease may arise. “It is so more important to monitor the eating habits of older pets,” stresses Tom Carpenter, DVM, president of the American Animal Hospital Association. “Generally, older pets do not need as much protein, sodium, and phosphorus. But your veterinarian needs to address this for your individual pet,” he says, adding that semiannual vet visits are recommended for an older animal.
 
Some mature dogs are prone to obesity. To test whether your dog is at a healthy weight, move your hands along his sides. If you can feel his ribs (but don't see them), he's doing okay. But if you feel a fat covering, or you visibly notice a rounded abdomen, he might be overweight. Exercise is still important for a senior dog, and if he's gained weight, you want to look for a low-fat weight-control food that contains vitamin-rich fish oils (IAMS™ ProActive Health™ Mature Adult is one good choice).
 
Other mature pets can become finicky eaters and lose weight as they age. 'Very old pets may actually need a more calorie-dense diet,' Carpenter says. Older dogs can lose their sense of smell and have a harder time chewing their food. To make mature dog food easier to eat, you can top their dry food with room-temperature wet food.
 
If your dog is gaining or losing a lot of weight, slightly decrease or increase his daily feedings. A sudden change in weight or appetite might be a sign of disease, so you should check with your vet. Water is also essential. 'Older pets are at a higher risk of dehydration,' Carpenter says. Provide a clean bowl with fresh water at all times.
