SOUTHBURY - State environmental officials were forced to euthanize a large black bear Saturday afternoon after the animal attacked two miniature horses, killing one of the animals. Chris Collibe, a spokesman for the state Department of Energy and Environmental Protection, said they were called in by state police to assist at a home near Bucks Hill Road on a report of a bear attacking the horses. When environmental officers arrived, Collibe said, the bear was attacking the miniature horses inside a closed pen.