A small number of countries — the UK, Ireland, Finland, Malta and Norway — require dogs to be treated for the tapeworm Echinococcus multilocularis shortly before entry, because they're working to keep the parasite out of their territory entirely. France is not one of them, since the parasite already occurs in parts of the French wildlife population, which removes the rationale for an entry-specific treatment requirement.
This matters most if your trip continues past France into one of the five countries that do require it. Arriving in France first, then continuing on to the UK, Ireland, Finland, Malta or Norway? You'll need the tapeworm treatment before entering that second country specifically, timed to a 24–120 hour window before arrival there — not before you land in France.
If your route is the reverse — leaving one of those five countries and arriving in France — the treatment you had done for that country's entry rules simply isn't needed again on the French side. It's one of the few places in this guide where the paperwork gets simpler, not more complicated, once you cross the border.