Dogs begin to show visible age-related changes at about seven to twelve years of age. There are metabolic, immunologic and body composition changes, too. Some of these are unavoidable. Others can be managed with diet.

1. Since smaller dogs live longer and don't experience age-related changes as early as bigger dogs, size is used to determine when it’s time to feed your canine a senior diet:
   Small dogs weighing less than 20 pounds: 7 years of age
   Medium dogs weighing 21 to 50 pounds: 7 years of age
   Large dogs weighing 51 to 90 pounds: 6 years of age
   Giant dogs weighing 91 pounds or more: 5 years of age
2. The main objectives in feeding an older dog should be to maintain health and optimum body weight, slow or prevent the development of chronic disease and minimize or improve clinical signs of diseases that may already be present.
3. As a dog ages, health issues may arise, including:
   • deterioration of skin and coat
   • loss of muscle mass
   • more frequent intestinal problems
   • arthritis
   • obesity
   • dental problems
   • decreased ability to fight off infection
    
4. Older dogs have been shown to progressively put on body fat in spite of consuming fewer calories. This change in body composition is inevitable and may be aggravated by either reduced energy expenditure or a change in metabolic rate. Either way, it is important to feed a diet with a lower caloric density to avoid weight gain, but with a normal protein level to help maintain muscle mass.
5. Avoid "senior" diets that have reduced levels of protein. Studies have shown that the protein requirement for older dogs does not decrease with age, and that protein levels do not contribute to the development or progression of renal failure. It is important to feed older dogs diets that contain optimum levels of highly digestible protein to help maintain good muscle mass.
6. Gamma-linolenic acid (GLA) is an omega-6 fatty acid that plays a role in the maintenance of healthy skin and coat. Although it is normally produced in a dog's liver, GLA levels may be diminished in older dogs. Does your older dog’s diet contain GLA?
7. Aging can affect a dog’s intestinal bacteria, which can result in symptoms of gastrointestinal disease. Senior diets for dogs should contain FOS (fructooligosaccharides) to promote the growth of beneficial bacteria.
8. Antioxidants such as vitamin E and beta-carotene help eliminate free radical particles that can damage body tissues and cause signs of aging. Senior diets for dogs should contain higher levels of these antioxidant compounds. Antioxidants can also increase the effectiveness of the immune system in senior dogs.
9. Routine care for geriatric pets should involve a consistent daily routine and periodic veterinary examinations to assess the presence or progress of chronic disease. Stressful situations and abrupt changes in daily routines should be avoided. If a drastic change must be made to an older pet's routine, try to minimize stress and to realize the change in a gradual manner.