Missing dog (Mammoth)

Our big, sweet dog went missing this past Monday afternoon.
He was last seen at 2:30 pm.
He is white with black spots on his body and a mostly black head.
He was wearing a red collar with his license tag on it.
He is the sweetest big baby ever and we miss him terribly.
If you see him please let us know.
He has never wandered off before so we are thinking he was most likely taken from our property.
Please help us bring home our dog, thanks!