The Age groups of dogs are defined by Petfinder as follows:
Baby 0-6 months, Young 6-24 months, Adult 2-8 years, Senior > 8 years.
Dogs between 2 and 3 years are sometime reported as "Young adults".
The AGE groups of cats are defined by Petfinder as follows:
Baby 0-6 months, Young 6-24 months, Adult 2-10 years, Senior > 10 years.
Cats between 2 and 3 years are sometime reported as "Young adults".