Place cream cheese, mayo, ketchup and horseradish in a medium bowl and mix well. Stir in green onions, corned beef, Swiss cheese and sauerkraut. Place in a small slow cooker and heat on low for 60 minutes or until bubbling.
Serve with mini rye or pumpernickel bread slices.
You can also use 1 cup of Thousand Island Dressing in place of the mayo, relish, horseradish and ketchup.