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.
It's just slightly more complicated than you may have expected. A rough approximation is that a 1-year-old cat is equivalent to about an 18-year-old human. By age 2, your cat jumps to around 25, and then gains about the equivalent of four human years in age each additional year. This is by no means an exact science, and different sources use slightly different calculations, but expect your kitty to start needing senior care around 65 -- which is to say, age 12 or so.