The boy, identified as John Bruno of Warrington, passed away Saturday at Children's Hospital of Philadelphia, according to police.
Last Wednesday, Bruno was playing outside with the 18-month-old hound, which the family says was not uncommon.
Police say the child's mother looked out and saw him lying face-down in the snow with the dog tugging at the scarf around the boy's neck.
The mother ran out of the house and found Bruno unconscious and unresponsive.
She untied the scarf, which police say was tight around her son's neck, carried him into the house, and immediately called 911.
Arriving paramedics performed CPR on the boy before transporting him to Doylestown Hospital, then onto CHOP.
The child's parents and older sister were at home at the time of the incident.
The Philadelphia Medical Examiner's Office will release an official cause of death.
Warrington police say this appears to be a tragic accident, but their investigation continues.
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