© Angela Antunes / CC by 2.0
The Belgian shepherd is understood to have bit the infant in the head at their rural property.
The tragedy happened at lunchtime today in the coastal town of Fasnia which is near the capital of Santa Cruz. It is not a holiday area.
The dog belonged to the family and was not on the dangerous breed list. The nationality of the young couple has not yet been revealed.
An investigation has been launched to find out what happened and how. The child's distraught parents are being comforted by relatives but have needed psychological medical treatment because of their extreme distress.
Reports say the couple found the dog with the new-born infant inside their home and separated them before calling the emergency services. Police and medics rushed to the scene, including a doctor and nurse from a nearby medical centre, and tried for more than half an hour to save the baby's life but without success.
Fasnia council has called a day of mourning from midnight tonight.
In a statement, the Mayor Damián Pérez said: "The death of a baby barely 20 days old, tragically in this municipality, has shocked the residents of Fasnia, expressing feelings of pain, affection and respect."
"A decree has been issued declaring a day of official mourning, from 24:00 hours on October 3 to 24:00 hours on October 4, 2018 throughout the municipality . The flags will wave at half mast in the municipal buildings and all the official public acts organised by the council suspended during this time."
"We want to show the condolence and solidarity of this council and of all the residents of the municipality to the relatives."
The dog was captured following the tragedy without any problems. It is understood to have shown no previous signs of aggression
And what does this do? Nothing. Why don't they decree that it's a crime for parents to leave their children in the company of dogs!!!