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.

Obesity is a common problem in dogs, but you can help your pet lose weight. Identifying the causes and following a total weight-management program can result in controlled weight loss and maintenance. A total weight-management program includes evaluating the animal, educating the pet owner, modifying behaviors, and tailoring the program to individual situations.
Obesity is defined as an increase in body weight, beyond the limitation of skeletal and physical requirements, resulting from an accumulation of excess body fat.
Obesity is caused when caloric intake exceeds caloric expenditure. This simply means that a dog eats more energy (calories) than it uses and stores the excess energy as fat.
There are many factors that can contribute to obesity:
Fat
Fiber and Fatty Acids
Carbohydrates and Special Ingredients
In addition, a diet that contains L-carnitine can help dogs metabolize fat. L-carnitine is a vitamin-like compound that helps burn fat.
A total weight-management program can lead to successful weight reduction in the obese dog. Complete evaluation by the veterinarian is always recommended, and owner compliance is essential to success.
IAMS™ and professional veterinary products provide optimum nutrition for animals that can benefit from a weight-management program.