This is what I've come up with, with help, so far. If you have anything to add to it, please mail me . The Drake Maijstral books Ferrets aren't actually mentioned, but the alien race Khosali is, which is very like ferrets in that burglary is a sport. That they have stiff spines is a misdirection. They work as ratters.
Someone is described as looking like a ferret that the hunters use on the plains.
I particularly like this reference as the book is set in Western Australia in the future, so the ferrets are obviously descendents of my ferrets. I can't remember which book. To say more would be a spoiler. Lyra's daemon turns into a polecat and a ferret. The ferret is described as the most evil of all it's manifestations.