No but it is very hard on their intestines so it's hard to digest I wouldn't suggest feeding it to them everyday but the occasional piece of cheese won't do much harm.
While they are not poisonous (having no venom), wild rats (not pets) can carry a variety of diseases. Actually, those purchased in pet stores make very good pets. I had one for a few years and he was...
Rat's teeth are not envenomed like a venomous snake's teeth are. A wild rat bite however might bring all sorts of disease and infection with it, but all of these are things the rat is carrying, not...