Heathcliff and the Catillac Cats - Season 2 - Eps 7: Dr. Heathcliff and Mr. Spike
Grandpa accidentally feeds Heathcliff some Super doggy Vitamins. Gradually, Heathcliff undergoes a startling transformation which includes barking at trucks and passing up fish in favor of bones. Worst of all, he finds himself feeling friendly toward Spike. Heathcliff eventually sets things straight by taking a massive dose of cat vitamins, with Iggy's help.
About Heathcliff and the Catillac Cats

Title: Heathcliff and the Catillac Cats
First Air Date: 1984-09-17
Last Air Date: 1985-10-07
Status: Ended
Rating: 6.3/10 (from 48 votes)
Language: EN
Seasons: 2
Total Episodes: 172
Network: Syndication FR3
Genres: Animation, Comedy, Kids
Production Companies: ICC TV Productions, DIC, DiC Entertainment
Cast

Mel Blanc
Heathcliff (voice)

Donna Christie
Cleo / Iggy (voice)

Peter Cullen
Pop / Max (voice)

Jeannie Elias
Jeannie Elias (voice)

Danny Mann
Hector (voice)

Marilyn Lightstone
Sonja (voice)