After Pongo and Perdita's 15 Dalmatian puppies have been stolen by Jasper and Horace, Scottie is one of the first dogs to answer Pongo's message, along with Danny, a Great Dane. Scottie asks Danny who was barking. He told Scottie that it's Pongo and tells him that 15 puppies have been stolen. They both signal the other dogs to form a "Twilight Bark" across London and the message reaches to Towser at Suffolk, who then sends it to his friend, the Colonel. Afterwards, Scottie isn't seen or even heard of for the rest of the film, but it can be assumed that when the puppies have returned home, he and the dogs realized that it was Cruella who was behind the 'dognapping' theft.
He also appears as a cameo, along with other dogs, during the "Twilight Bark" sequence. He is the first dog to pick up the Dalmatian puppies' barks. However, this could possibly be a different Terrier, since their Human refers to him as a female.