The Scooby-Doo/Dynomutt Hour - Season 1 - Eps 13: The Harum Scarum Sanitarium
Going to Niagara Falls the gang ends up staying at an asylum being haunted by the ghost of Dr. Coffin. His two henchmen seem to be driving an ambulance taking patients, but are they really patients or are they hiding something?
About The Scooby-Doo/Dynomutt Hour

Title: The Scooby-Doo/Dynomutt Hour
First Air Date: 1976-09-11
Last Air Date: 1976-12-18
Status: Ended
Rating: 7.9/10 (from 167 votes)
Language: EN
Seasons: 2
Total Episodes: 32
Network: ABC
Genres: Animation, Comedy, Family, Kids, Mystery
Production Companies: Hanna-Barbera Productions
Synopsis
The Scooby-Doo/Dynomutt Hour is a 60-minute package show produced by Hanna-Barbera Productions in 1976 for ABC Saturday mornings. It marked the first new installments of the cowardly canine since 1973, and contained the following segments: The Scooby-Doo Show and Dynomutt, Dog Wonder.
Cast

Henry Corden
(voice)

Allan Melvin
Additional Voices (voice)

Casey Kasem
Shaggy Rogers / Additional Voices (voice)

Julie McWhirter
Additional Voices (voice)

Micky Dolenz
Supporting Voices / Additional Voices (voice)

Don Messick
Scooby-Doo / Additional Voices (voice)

Gary Owens
Blue Falcon (voice)

Virginia Gregg
Additional Voices (voice)

Larry McCormick
(voice)

Heather North
Daphne Blake (voice)