How old is old? The average lifespan of a dog has increased from seven years in the 1930s to about twelve years today. Many dogs will still be frisky when they're ten, while others only want to lie by the fire at the same age. As a rule, smaller dogs live longer than bigger dogs. A Yorkie may not show signs of age until it's eleven or twelve, while a Great Dane is getting on in years by the time it's eight. Just like humans, dogs are more susceptible to health problems as they age. You might want to make more frequent checkups at the vet as your dog reaches its golden years. Some of the signs of age-related conditions to watch for: a sudden change in weight or appetite, or an increase in appetite without gaining weight can indicate a serious condition that requires immediate veterinary care. Difficulty moving can be a sign of arthritis. Excessive coughing or panting are indicators of heart trouble. Increased water consumption and urination could mean diabetes. All dogs, like people, become less active as they get older. You might want to switch to a dog food specially designed for older animals to fulfill your dog's new nutritional needs. And don't forget the most important nutrition: older dogs still need lots of love.