Family Dog Fatally Mauls 3-Day-Old Baby The dog was startled when the baby's mother coughed By Newser Editors and Wire Services Posted Apr 22, 2016 6:59 PM CDT 495 comments Comments Police say Polo bit and killed his owners 3-day-old baby. (San Diego County Department of Animal Services) (Newser) – A 3-day-old boy was fatally mauled by a pet dog as his parents watched helplessly in their San Diego home, the AP reports. Sgt. Tu Nguyen said the parents were in bed watching TV with their newborn son and pit bull-mix Thursday night when the mother coughed, startling the dog. Nguyen said the dog reacted by biting the baby, resulting in a traumatic injury. He said the parents pulled the animal off and took their only child to the hospital, where he was pronounced dead. Nguyen called it a "tragic accident." The San Diego Union-Tribune reports animal control officers took the 2-year-old dog into custody.