Just like people, dogs slow down as they grow older. Their hair turns gray, their eyes dim, their bodies lose tone and energy. They become more susceptible to illness, less adaptable to change and even forgetful as time marches on. They look to you for help and comfort.

When Is Your Dog "Old"?

The old rule-of-thumb that one dog year equals 7 years of a human life is not exact. The ratio is higher with youth and decreases a bit as your dog ages. Depending on the breed, a dog experiences the raging hormones of adolescence anywhere from 8 months to 2 years or more. Generally, a dog of 6 has aged about as much as a 45-year-old human. At 10, she's like a human of 65; at 12, a human of 75; and at 15, a human of 90.

You are the best judge of your dog's stage of life. Even if she is in the best of health, it's important that you notice when your dog begins to show her age. After years of constant companionship, however, you may not see the first subtle signs of decline. No matter how close you are, your dog does not know how to communicate little aches and pains, and even some bigger discomforts to you. She doesn't understand what's happening to her when she can't run as fast or jump as high.

When to Screen for Aging

Most veterinarians recommend that your dog be screened for the symptoms of aging and then come for twice-yearly visits when she is a senior. To determine when it's time for the first screening, you have to understand how your dog's medical history and breed might hasten or stave off her senior symptoms. Then, factor in these recommendations:

For dogs over 80 pounds, begin geriatric screening between ages 4 and 6.

For dogs 51 to 80 pounds, begin to screen between 6 and 8.

For dogs 16 to 50 pounds, begin to screen between 7 and 9.

For dogs 15 pounds or less, begin to screen between 9 and 11.