I have done a little research as to why grapes and raisins are toxic to dogs and whether that toxicity may be applicable to rabbits.
Moulds affect grapes with Aspergillus being the main mould. In turn these produce mycotoxins such as ochratoxin A, patulin, aflatoxin and citrinin. Moulds and mycotoxins are the main reason penicillin cannot be administered orally in rabbits. In many grapes and dried vine products penicillium is also present.
"Aflatoxins are potent carcinogens.
Patulin causes gastrointestinal problems, skin rashes, and is known to be mutagenic. This mycotoxin has been shown to be neurotoxic, immunotoxic, immunosuppressive, genotoxic, teratogenic and carcinogenic.
Citrinin has been shown to be hepato-nephrotoxic in a wide range of species."
Sorry to derail the lovely Lola's thread.