Spanish police have arrested a Venezuelan veterinarian wanted by the US for allegedly trafficking heroin by implanting it in puppies.

A Civil Guard spokeswoman on Tuesday said 33-year-old Andres Lopez Elorza was arrested Saturday in the northwestern town of Santa Comba where he had been hiding after the National Court authorized his extradition last month. The officer spoke on condition of anonymity in keeping with police regulations.

Police said Colombian authorities discovered 6.6 pounds of heroin implanted in three puppies during a 2005 raid on a clinic the vet ran in Medellin. The statement said the vet was a member of drug-trafficking gang that used dogs to send liquid heroin from Colombia to the United States.

Lopez was arrested in Spain in 2013 but released while his extradition was being considered.

The spokeswoman said Lopez had been living in Spain for eight years and was married with two children. She said he had been working as a vet for two companies, his employers spoke highly of him and he had no record of drug-trafficking in Spain.