Id give your vet a ring. Do they specialise in exotics?
I dont know much about chins, but if their guts are similar to rabbits in the way that they eat constantly to keep them ticking over, then i would have thought it might be an idea to try a bit of syringe feeding.
I could be way off the ball though.
Ive found this link, it might be of help..
http://www.chinnitude.com/neuter.htm