No matter how big they get, we like to think of our dogs as eternal puppies who will be with us forever. As much as you may wish to deny that your pup is getting older, it's important to keep an eye out for senior dog health conditions so that you can help improve his quality of life. Keep reading to learn about common health problems in senior dogs that might one day affect your pet. When Is a Dog Considered Senior? On average, a dog is considered senior when he reaches seven years of age, although it really depends on the size and breed of the dog, says the American Veterinary Medical Association (AVMA) . Very large breeds age more rapidly than small breeds. While a Great Dane would be considered a senior by age six, a tiny Chihuahua may not reach old man status until eight or nine years of age. Of course, other factors, such as genetics and environmental conditions, can affect how rapidly individual dog ages. Once your dog starts showing signs of age-related health issues, he