General Rules for Pet Owners in Spain
All domestic pets in Spain must be identified by microchip or by a clearly readable tattoo. The tattoo will only be accepted as a means of identification until 3 July 2011.
Vaccination against rabies is compulsory. It is also advisable to have dogs vaccinated against other diseases such as distemper and hardpad. Cats should be immunised against feline gastro enteritis and typhus.
There is no law against dogs fouling public places, however people are becoming increasingly sensitive about it and there are specific rules within certain places, such as urban parks.
Dogs should be kept on a lead in public places.
Generally, dogs are permitted on trains. Sometimes they may need to be contained in a pet carrier, or they may have to be muzzled. Dogs normally travel at half the fare of a 2nd class ticket; this charge is payable directly to the conductor