Make sure the dog is vaccinated.
If you haven't done it yet, do an obligatory theory course BEFORE you go to Spain.
Pay customs (if the dog's price is over 300 CHF).
Visit a vet with your dog within 10 days after your arrival.
Basically, this is the website with all necessary info: http://www.blv.admin.ch/themen/04670...x.html?lang=en
If you use the search option on this forum, you will find lots of information too.