Other tips for a healthy older dog:
Offer your dog fruits and vegetables. All dogs benefit from eating small amounts of fruits and vegetables, particularly when they're older and more prone to constipation. Add fiber to your dog's diet in the form of wheat bran, steamed fresh green beans or canned green beans, or plain canned pumpkin.
Add extra nutrients. Antioxidants such as vitamin E and beta-carotene, omega-6 fatty acids such as gamma linolenic acid (GLA), and fructooligosaccharides (FOS) can help boost an older dog's immune system, burnish his skin and coat, and support healthy digestion. Many of these nutrients are baked into high-quality foods. Increasingly, people are feeding these nutrients to dogs in the form of nutritional supplements as well. Because dogs often develop arthritis as they age, vets increasingly suggest adding a daily glucosamine-chondroitin supplement to his diet as well.
Check with your vet about special dietary needs. Dogs with kidney disease, for example, should switch to low-protein diets. Your veterinarian can prescribe an appropriate food or refer you to a veterinary nutritionist who can help you devise a suitable homemade diet.
How much?
Most older dogs gain a little weight over the years because they're just not as active. If your dog is in this club, dole out less food to compensate for fewer calories burned.
A less frequent occurrence is when dogs become thinner with age. While not always the case, weight loss can be a sign of health problems. So if your older dog is losing weight, take him in for a vet exam to rule out any medical conditions. Some solutions may require minor adjustments. For instance, your dog may be found to have dental problems that make it difficult to chew food. If that's the case he might benefit from switching to smaller-sized kibble, or canned food.