Ruff and REDDY, Don. The first Hanna-Barbera show, 1957-1960, 1962-1964. And I remember the theme song just as you do.

To steal from www.toontracker.com/ruffredd/ruffredd.htm:

Ruff and Reddy featured a brainy cat, Ruff, and a brainless dog, Reddy. Teamed with the kindly Professor Gismo, they faced such evil-doers as Killer and Diller, the terrible Texas twins, Captain Greedy and Salt Water Daffy, the chicken-hearted Chickasaurus, the Goon of Glocca Morra and others in various madcap adventures.
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And your favorite episode, "The Mad Monster of Muni-Mula," can be found there in RealVideo.