It depends on the breed of dog, but your pet's senior years generally begin at age 7. Louise Murray, DVM, director of the ASPCA's Bergh Memorial Animal Hospital in New York City and author of Vet Confidential (Ballantine, 2008), tells you what you need to know to keep your older dog spry and happy.
At this stage, Murray recommends taking your dog to the vet twice a year. 'So much can happen to an elderly dog,' she says. Your veterinarian can take blood annually to test liver and kidney functions. 'Discovering problems early is extremely important,' she says. Your vet can be on the lookout for conditions that often affect older dogs, such as anemia and arthritis.
Pay attention to what might be subtle changes in your dog's habits: Is she drinking more water or urinating larger amounts? These behaviors might indicate a liver or kidney problem. Have your dog's bowel movements shifted? This could indicate a digestive issue. Diabetes or digestive problems might cause your dog to eat more but still lose weight. Knowing the dog's patterns can help the veterinarian determine a course of treatment.
Continue to use preventive medicines.
Clean your dog's teeth daily. If she has tartar buildup, you might need to have her teeth professionally cleaned at your vet's office, which requires sedating your pet.
Your dog is probably less active, so steady, moderate exercise is best for her now. Don't turn her into a 'weekend warrior' who, after lying around on weekdays, accompanies you on a 10-mile hike on Saturdays. This is especially hard on an older dog's joints.
Your veterinarian might wish to put your dog on a senior diet, such as IAMS™ ProActive Health™ Senior Plus. These formulations contain nutrients specifically geared toward older-dog health.
Does your mature dog sniff at his bowl and walk away instead of digging in? You may think he’s just being picky, but it’s important to keep an eye on how much he’s eating — especially if he’s a senior. While age-related diminishment of the senses of smell and taste may account for some of his disinterest in food, appetite loss can also indicate a serious medical problem.
“It’s important to give your dog enough calories because weight loss can be debilitating to senior pets,” says Wendy Brooks, D.V.M., who warns that a loss in appetite should be mentioned to your vet. A good rule of thumb: If your pet hasn’t eaten in a day, make a visit to the vet. Here are six ways to entice your canine friend with a nourishing meal.

Many animals find canned food more palatable because they like the taste and texture, Brooks says. You can top their favorite dry food with room-temperature wet food.
Dogs like a warm or room-temperature (not hot or cold) meal. Avoid serving him day-old wet food from the refrigerator, and keep his food away from heat. Another reason he might not be eating: It's too hot outside.
Dogs prefer consistency when it comes to their food. Don't change every day, but try a new flavor, such as lamb or chicken, and see if he responds (it may trigger his sense of smell). To avoid an upset stomach, introduce a new food by mixing it with his old food in equal increments each day.
Common mature-dog health issues, such as arthritis or joint pain, can make it difficult for him to access his bowls. Keep food and water where he spends most of his time. Put a water bowl on all floors of the house, too.
Older pets are at a higher risk of dehydration. Provide a clean bowl with fresh water at all times. It will help prevent disease, such as a kidney condition, and aid in digestion.
Dogs are people pleasers. If you see him eating, give him a little verbal reward. He'll know it makes you happy and will repeat the behavior.