The clowns of the Ringling Bros. and Barnum & Bailey Circus perform an abbreviated version of the classic Horse Race Gag with Mike Douglas on "Highlights of the Greatest Show on Earth" television special in 1968.
The clown who approaches Douglas at the beginning of the clip is Doug Ashton, the jockeys look to be (from left to right) Bobby Kay, Mark Anthony and Lazlo Donnert (who slaps Doug Ashton to the ground at the end). Mike Padilla is the photographer capturing the "photo finish" and Frankie Saluto is standing in the ring, mostly obscured by Douglas until the very end.
I understand that the gag was produced by Mark Anthony, who I'm told never much cared for it. I don't think that it was ever performed again on Ringling after 1969 but the gag enjoyed an extremely long life on the Clyde Beatty-Cole Bros. Circus where it was performed quite frequently.