Whereas previously only small pooches were allowed on the metro, dogs of all sizes will now be able to accompany their owners at most times of the day.
Only peak travelling hours – 7am to 9 am and 5 pm to 7pm – are no-go times for dogs.
The animals will also have to wear a muzzle and a microchip under their skin in order for authorities to be able to identify them.
The new legislation also states that it can only be one pooch per person and that under 16-year-olds cannot travel with the more dangerous breeds.
It’s forbidden for dogs to occupy any seats in the carriages and once they get off the metro they mustn’t go on the escalator.
Dog owners will be fully responsible for their pets’ behaviour and will face fines if they let their animals off the leash or put other passengers in danger, local Catalan daily La Vanguardia reported.