We asked a friend of ours recently if she would be willing to contribute a photo of her two dogs, who are 7 and 9 years old, to our Senior Dogs Project. She bristled a little and then said, "My dogs aren't senior! They don't act old. They run and jump and play just as they always have."
Like people, dogs are individual in the way they age. Certain breeds, mixed breeds, and, in general, smaller dogs tend to live longer. A small dog of less than 20 pounds might not seem to show any signs of age until she is 12 or so. A 50-pound dog won't seem old until about 10. Larger dogs begin to show their age at 8 or 9.
It's encouraging that the average span of life for dogs has increased from 7 years in the 1930's to more than 12 years today. With the right care, it's not uncommon for quite a few dogs to live to 14 or 15 these days.
To give you an idea of the relationship between a dog's age and a human's, it is generally accepted that a dog of 6 is roughly equivalent to a human of 45. At 10, a dog is equivalent to a human of 65. At the age of 12, he is the same as 75 year-old; at 13, he is an 80-year-old; at 14, an 85-year-old; and at 15, he is like a human of 90.
Using established guidelines to determine when your dog might qualify as a senior will help you to understand changes in behavior or to anticipate a change in health status. On the basis of your knowledge, you will be better able to identify and approach health problems in an early stage, when they may be more easily treated.
Most vets recommend that you begin a geriatric screening for your dog at an appropriate age. This is related to your dog's size in the following way:
Up to 15 pounds Begin geriatric screening at age 9 to 11
16 to 50 pounds Begin geriatric screening at age 7 to 9
51 to 80 pounds Begin geriatric screening at age 6 to 8
Over 80 pounds Begin geriatric screening at age 4 to 6 (This material on geriatric screening is based on information provided by Ocean Avenue Veterinary Hospital, San Francisco, CA.)
Other factors that influence your older dog's aging process and that may determine the age-related problems she may eventually have are:
Genetic Background -- Some breeds are known to have specific health problems. Golden Retrievers and large breeds, for example, are known to develop arthritis in back and hips as they age.
Nutrition -- Good nutrition will retard the aging process.
Illnesses & Disease -- A serious illness or disease can shorten a dog's life.
Control of Environmental Factors -- Keeping your dog and his environment clean and free of parasites will increase the chances of long life.
In general, a geriatric screening of your dog will include: (1) a thorough, hands-on physical exam; (2) blood tests; (3) possibly an electrocardiogram; (4) specialized tests depending on your dog's health history.

Many vets advise semi-annual visits once your dog becomes a senior. In between visits to the vet and annual geriatric screenings, you can stay alert to behavioral changes and other signs of aging. Here are some things to watch for and action to take:
Sudden loss of weight can be extremely serious. Take your dog to the vet as soon as possible.
Serious loss of appetite -- to the point that your dog is eating almost nothing. See your vet right away.
Increase in appetite without increase in weight may mean diabetes. Get to the vet as soon as possible.
Diarrhea or vomiting, if it lasts more than a day can be a sign of many problems. Don't wait to see the vet.
Increased thirst, without a change in activity level, and increased urination are other signs of diabetes. Your dog should be tested as soon as possible.
Tiredness/fatigue when exercising is natural as a dog ages. Continue an exercise program, but modify it in order not to overtax your dog. Difficulty in getting up from a lying position, or other problems with moving may indicate arthritis. Your vet will be able to advise you on ways you can relieve your dog's discomfort and lack of mobility.
Coughing and excessive panting may indicate heart disease. If these symptoms persist even after you've modified your dog's exercise program, visit the vet.
Problems with vision and hearing are natural as a dog ages. Accommodate these changes as best you can -- by not changing the location of furniture, for example, or clapping instead of calling your dog's name when he no longer seems able to hear you.
Acting abnormally -- for instance, roaming in circles, barking at nothing, being withdrawn, having "accidents" in the house -- all may be indicators of illness or disease. Consult your vet right away.
Graying hair and drying skin are sure signs of aging. More attention to grooming and the introduction of massage will help the condition of the skin and coat.

©1997, The Senior Dogs Project (reprinted with permission)