Rowlf the Dog and Baskerville the Hound were created for this series of Canadian Purina Dog Chow ads, which aired from 1962 to 1963. Seven spots were produced -- three 60-second ads, and four product IDs.
According to Jim Henson: The Biography, "Bernie Brillstein later recalled - though he was never certain if the offer came from Purina or another client - that Jim was offered $100,000 for the company to own Rowlf outright. Brillstein nearly lept at the offer, but Jim immediately squashed the deal. :Bernie", warned Jim, "never sell anything I own.""
Four commercials were included as bonus features in The Muppet Show: Season Three DVD set.