Oooooer, now, that gets into trickier territory! After all, real live living dogs that aren't actually robots require things like food and being walked, attention even, and while I could easily smuggle a robot dog in to work with me and even claim I was doing it for research, I suspect that my coworkers wouldn't take it quite so well if I had an extra mammalian lifeform under my desk.
Canine, probably someone would be allergic, I'd get complaints about the smell, and told that I had to dock my pay for the time spent walking him or her around.
Human, probably someone would be – well, not allergic, but I'm sure someone would complain that I was offering unfair working conditions and also sub-contracting illegally or some such. Alternatively, that I hadn't brought enough for the whole class to share, as it were.
I take it, meanwhile, that you are not actually a librarian, are you, Jane.