This is one of those strips that I know next-to-nothing about, but I'll give it a shot, anyway.
Kelly & Duke was one of the first strips picked up by the newly established Universal Press Syndicate. It ran from 1972 to 1980. The strip's title was originally just Kelly, but the title changed in 1974. The cartoonist was Jack Moore.
The strip was about a boy (Kelly), and his dog. Duke was a big, talking dog who always walked on his two legs and had a southern accent, evident by how he talks. Once in a while, a beatnik cat named Roscoe showed up.
Beyond that, I don't know much about the strip. I have no idea what happened to Jack Moore, and what his cartooning history are (assuming he has any besides Kelly)
The only reason I've heard of this is because the strip is often mentioned in comics forums and newsgroups. The strip had fans, at least.
I've found few samples of the strip. The strip was pretty unusual at the time. The artwork caught my eye. It was sorta inbetween the cartoonish style and the "serious" style seen in soap strips. Maybe that's why it had fans.
Universal Press seemed to had a goal in what comics they were looking for, judging by this and two other comics they picked up at the time, Doonesbury and, some may argue, Ziggy.
If anyone has more information about Kelly & Duke and the creator Jack Moore (including more samples, articles, etc...) please email me at firstname.lastname@example.org
EDIT (7/27) - Well, that was fast. I've found more samples at this site. I've also ordered some Sunday samples from eBay. I'll post some when I get them.