When you look at the current research on spaying and neutering, the AGE at which it's done turns out to be vitally important to your dog's future health. For example, your female dog should NOT be spayed at 6 months old.
Life Expectancy of Dogs and Cats. We hope our pets will be a part of our lives for many, many years but the fact is that the average life expectancy is 10-12 years for dogs and 10-14 years for cats. Older pets have very specific needs and are particularly susceptible in later years to cancer, arthritis, and dental disease.
At one year a cat is about equal in development to a human at age 15. The cat is an adolescent, approaching adult size but not yet fully grown, capable of mating but not likely to be mature enough for really effective parenthood, still kittenish in some ways but becoming more like an adult in other ways. At age 2 a cat is about like a human at age 23, all grown up and established in young adulthood. After that cats age about four times as fast as we do, so you can add four equivalent human years to each additional year of feline age. That makes a cat at age 3 about equal to a human of 27, 4 is like 31, and so on.