Cat years aren't the same as dog years
Cats age differently than both dogs and people. A 1-year-old cat resembles a high school sophomore. A 2-year-old cat would be legal to drink in most states. After that, each cat year is "worth" approximately four human ones.
Cats start to show aging changes between 7 to 10 years of age. Since most cats live longer than dogs, they spend relatively more of their life as a "senior" pet.
Age is not a disease
Although age may not be a disease, the likelihood of disease does increase with age.
Cats are experts at hiding illness, so you must be watchful.
The belief that cats don’t get arthritis is simply not true. Signs may be as subtle as difficulties with jumping, grooming or using the litter box.
These difficulties may cause trouble if the cat can’t reach its food and water located up on a counter, its hair becomes matted up on the back end, or the cat starts going to the bathroom outside of the litter box.
This is when changes to the environment need to be made. Make sure your cat has easy access to food, water and the bathroom. This means that your cat needs a short litter box on each floor that doesn’t require the high jump to get inside.
Besides arthritis, there are other reasons a cat might have inconsistent litter-box habits.
Constipation is common in aging cats. If stools are hard as a rock, and these "rocks" are being left all over the house, discuss with your veterinarian the possibility that your cat might need a stool softener.
If your cat has started "flooding" the box with increased amounts of urine, a medical issue such as diabetes, kidney failure or hyperthyroidism might be to blame.
Mild weight loss can occur with increasing age and loss of muscle tone, but significant or progressive weight loss can indicate a medical problem.
Diabetes, kidney disease, hyperthyroidism, heart disease, and cancer are arguably the top five causes of weight loss in cats.
On the other hand, weight gain is a frequent problem for older, indoor cats because of the commonly provided all-you-can-eat buffet and decreased activity level.
Obesity can contribute to other diseases as well, making arthritis worse and diabetes more likely.
Environmental enrichment and exercise
Although this is important at any age, it’s even easier to neglect this as your cat slows down to a lifestyle of shifting sleeping positions in the sun. Many people believe that their cats won’t play with them, but it’s quite possible that they just haven’t figured out how their cat likes to play yet.
Cats like movement and interaction. Their toys have to do something, not just sit there. This means that the human element has to put some effort in (or at least some batteries).
Try sparkle balls, feathers, crinkle balls, paper bags (not plastic, which are dangerous if ingested), tie a string to a fur mouse and pull, play laser light tag, or use your imagination.
Some cats like to explore cardboard boxes or laundry baskets. Pick up the toys after play, to keep the items more novel, and to prevent ingestion of them which could lead to intestinal obstruction.