All female dogs have nipples. Usually about 6 or 8. Although it
does vary and can even be odd number. They aren't always obvious
until they have had a season. Then they are usually more
prominent.
There are sometimes a couple on the chest area that aren't very
visible. All of them have them though. People who claim to have
females with no nipples just can't see them as they have had them
spayed before their first season.