First of all we'd better define what we mean by a senior dog. We humans tend to think of ourselves as Senior Citizens when we get to the age of 60-65 years, even though the joints may start creaking a few years before this!
The 'one human year equals seven dog years' rule is an easy way to calculate and relate to your dog's age, but doesn't necessarily apply to all breeds. Large breed dogs (i.e. Great Danes) are considered a senior at 6 or 7 years of age, whereas small breeds (i.e. toy poodle), aren't considered a senior citizen until they reach into the teens of years.
Basically, if your dog is 7 years or older, you ought to be considering him or her to be at least middle aged if not senior and therefore need to consider how best to care and feed them. This is because, like humans, requirements for exercise and nutrition change with age, and there may be a case for including a food with added 'extras' for joint care.
As your dog reaches his senior years, remember these tips:
Minimise stress and change.
Avoid big moves or changes in your dog's schedule. If you must disrupt a routine, give your dog some added attention to ease the adjustment. Regular exercise.
Taking your dog for two 15-minute walks each day helps maintain muscle tone, enhance circulation, promote digestion and prevent weight gain. Smaller, more frequent meals.
Instead of one large portion a day, try two or three smaller meals, which also will help increase your dog's metabolism, burn calories and provide all of the needed nourishment.
Regular dental care and thorough physicals will help you identify subtle changes in your dog's health. At home, take a few minutes each month to closely examine your dog for any irregularities such as odd-shaped bumps or lumps. If you do discover something unusual and it seems to be growing rapidly, call your veterinarian. Early detection and preventive treatment can go a long way toward extending life expectancy. Nutrition.
In general, dogs of seven years and older start taking life a bit easier and, as a result, their nutritional needs begin to change once more. With large breeds, this change will take place at around six years of age Senior dogs are less active and have a slower metabolism, so can be even more prone to gaining weight. Equally as they reach their geriatric years, illness and blunting of the senses of taste and smell mean it can be hard to maintain a good body condition.
In their senior years dogs need a high quality, palatable diet with easy to digest protein, lower calorie levels and a careful balance of other essential nutrients.