Scooby-Doo and Scrappy-Doo (1979 TV series) threatening cancellation for the show, whose ratings were in decline. ABC was going to choose between two shows-Scooby-Doo or an unnamed pilot from Ruby Spears Enterprises. Therefore, for its 1979–1980 season, "Scooby-Doo" was given a major overhaul, adding the character of Scooby's nephew Scrappy-Doo, voiced by Lennie Weinrib, and changing the name of the show to "Scooby-Doo and Scrappy-Doo". Although still present in these episodes, the characters of Fred, Daphne, and Velma became less essential to the plot and Shaggy, Scooby and Scrappy were the main focus. Marla Frumkin took over Pat Stevens' role as Velma Dinkley towards the end
Scooby-Doo joined with a new Hanna-Barbera show, "Dynomutt, Dog Wonder", to create "The Scooby-Doo/Dynomutt Hour" (the show became "The Scooby-Doo/Dynomutt Show" when a bonus "Scooby-Doo, Where Are You!" rerun was added to the package in November 1976). Joe Ruby and Ken Spears, now working for Silverman as supervisors of the ABC Saturday morning programs, returned the program to its original "Scooby-Doo, Where are You!" format, with the addition of Scooby's dim-witted country cousin Scooby-Dum, voiced by Daws Butler, as a recurring character. The voice cast was held over from "The New Scooby-Doo Movies" save for Nicole Jaffe, who retired from acting