For my cats' picky tastebuds (and in elderly Bac's case, tricky tummy), I can lovingly select and pay mucho currency for duck, or pure chicken, or lamb, maybe even kangaroo (that last might just be in the dog food). And I do. And they are paragons of beauty and health, much more so than their person, I might add. But think about it:
How come and why for no mouse flavor food?
Luckily for me and you, somebody beat me to this question over at The Straight Dope a while ago. The answer is pretty plausible. With a dash of icky.