There an original terror dog on ebay, wasnt actually used for filming though. slightly pricey I thought that being the case.
The description is
Up for auction is a Terror Dog animation puppet created during the production of hit comedy Ghostbusters. This puppet is constructed of Latex rubber skin, foam Latex inside, and a wire armature for structure. It was designed and sculpted by Randall William Cook, who went on to win three Oscars for his animation supervision of the characters in the Lord of the Rings series. This particular Terror Dog was an early pull from the molds. It was not intended for use during filming and subsequently did not receive an articulated stop-motion armature. This puppet was acquired 10 years ago directly from a Boss Film crew member who worked on Ghostbusters. 5 years ago it was sent to another former Boss Film Creature Shop employee who carried out the preservation of the puppet. This item is in outstanding condition. The skin and foam is still soft and flexible insuring a long life ahead. It measures roughly 18” length x 10.5” width x 11” height. Puppet comes with a wooden base and acrylic outer case (25” length x 16” width x 16” height). Temple doors seen in photos is not included in this auction.