The search is continuing for 32-year-old Antonio Ortega who disappeared in Torremolinos on 22 January while walking his dog.
The pet, called Smuky, was found last Sunday running lose in the motorway tunnel near Churriana, behind Torremolinos, but there was no sign of Antonio.
His family are especially worried as he needs to take regular medication.
The dog showed signs of having tried to escape from a gully or hole, and the emergency services say this gives them hope that Antonio can still be found. Antonio is described as 180cm tall and weighting 72 kilos. He has short brown hair.