Bringing a dog, cat or ferret into Spain from another EU country comes down to the same three EU-wide requirements that apply everywhere in the bloc, confirmed directly by Spain's Ministry of Agriculture, Fisheries and Food (MAPA). First, an electronic microchip (a pre-2011 legible tattoo is also accepted). Second, a rabies vaccination, given once the pet is at least 12 weeks old, which becomes valid for travel 21 days after it's given. Third, a valid EU pet passport, issued by an authorised vet, with the rabies vaccination section correctly completed.
MAPA's own guidance is explicit on one point that trips owners up elsewhere: an animal under 15 weeks old cannot be vaccinated in time to meet the 21-day rule, and is therefore not authorised to enter Spain at all. If you live outside the EU, the pet passport doesn't apply to you; you'll need a health certificate from an accredited vet instead, confirming the same microchip and vaccination requirements, and if you're arriving from a country not listed in the EU's low-risk annex, a rabies antibody blood test taken at least three months before travel as well.
Spain does not require a tapeworm treatment for dogs entering the country, unlike the UK, Ireland, Finland, Malta and Norway — MAPA's guidance confirms the treatment only matters on the way out, if your onward route takes you into one of those countries. The one requirement that has no EU equivalent at all is specific to Spain: certain dog types fall under its potentially dangerous dog (PPP) licensing system, covered in its own article in this section — it doesn't block entry, but it does require registration once you're here.