The "Ruff & Reddy Show" was the first Hanna-Barbera cartoon made for U.S. television. What kinds of animals were Ruff and Reddy?

"The Ruff & Reddy Show" is a Hanna-Barbera animated series that followed the adventures of Ruff (voiced by Don Messick), a smart and steadfast cat, and Reddy (Daws Butler), a good-natured and brave but dumb dog. This show was first broadcast in December 1957 on NBC. It was the first television series produced by Hanna-Barbera, and it made pioneering use of limited animation techniques.

On the show, Ruff and Reddy were not adversaries. They were housemates and truly best friends.