O’Reilly, the publisher of computer books, is known for depicting various fauna on their books’ covers. Being that I am interested in Mac computing, I noticed that the books pertaining to versions of Apple’s OS X, like Panther and Jaguar, do not feature big cats on their covers. Instead, they feature dogs. Now, why would O’Reilly do a seemingly illogical thing like that? Choosing a panther for a book on OS 10.3 would be the easiest thing to do. But no, they chose a beagle instead.

This year’s Macworld gave me the opportunity to ask someone at the O’Reilly booth the reason why cats aren’t being used on OS X books. The nice lady behind the counter told me that for Macintosh book covers, they’ve always used dogs. This is confirmed by a post at MacSlash by an O’Reilly employee:
We chose to use dogs on the covers of our Mac books long before Apple chose to release versions of Mac OS X with kitty names.
Our earliest Mac book, REALbasic: The Definitive Guide, sported a greyhound on the cover, so we decided to follow that motif and run dogs on the cover of all of the Mac books. There’s a bit more to this story, but that’s basically the gist of it.
I wonder whether O’Reilly’s decision to initally use a dog has something to do with Apple’s unofficial mascot back in the day, the dogcow. This was a system icon of a dog that was often mistaken for a cow. Now that’s one hoofed animal I don’t think you’ll ever see on O’Reilly’s covers.