I was going to say that the animal on the cover ought to be a human, given that furries (et. al.) are animals of a sort, and what’s on the cover should be “opposite” somehow to the reader, but then I realised that the book is for someone who presumably isn’t a furry, and so the cover should indeed be some kind of animal.
The potential problem is that the animal should be entirely unrelated. The wolf (dog? canid?) is thus a bad choice because - from what little I’ve seen - canids seem to be pretty common preferences*. Thus it ideally should be an animal that it’s incredibly unlikely anyone would identify with. Or as.
Thus, may I suggest: a paramecium
* I’m not sure “preference” is the right word here. I may need a copy of this book.



I know that book well, and have seen many O’Reilly covers. It was the source of my assertion that the animal should be entirely unrelated, although I admit there are some hints in that specific book that they chose the camel - presumably from a shortlist - on purpose, to be loosely representative of Perl, so maybe I was a little off base with “entirely”.