Unlike humans, there is no legislation that says that at insert-local-legal-age-here a dog becomes an adult. However, there is a lot of information (mostly on food) that is different depending on if your dog is a puppy or an adult.

At 11 months old, I have no idea if my dog is a puppy or not! How can I tell?

I realize that this question is similar to this one (At what age can my dog be considered old?) that was closed for being opinion based. But as I mentioned, since there are a lot of products targeted at "puppies" and at "adult dogs" I believe that there has to be a factual answer out there, at least in the eye of the food industry.


Karen Overall, in her book Manual of Clinical Behavioral Medicine for Dogs and Cats describes some general numbers:

  • Until sexual maturity is the juvenile/puppy phase
  • 6-9 months is sexual maturity and adolescence
  • 12-18 months is the start of social maturity and ends at about 24 to 36 months where the dog is considered adult.
  • 6-10 years marks entering into senior territory

In some senses it will depend on what you mean by "adult" because, as with humans, it's not entirely an age thing. We may call a person an adult at 18, but few seldom really are, that's a legal designation.

So, depending on the breed, you're talking about social maturity and that's at or around the 2 year mark, give or take. It really has breed variance, so average breed lifespan as a comparison would place any given dog at some point in those ranges and you can use that as a bit of a guide for your dog.

The periods described are also described in this article: Dog Ages & Dog Stages which is backed up by the research information in Karen Overall's book.

  • 1
    I would add that breed also matters. Some breeds are natural born clowns (eg, retrievers) and don't seem to "grow up" until they're 4-5 years old, while other breeds (eg, shepherds) seem quite "grown up" by two. Mar 17 '14 at 19:23

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