I have 5 mice and now 3 out of 5 are sick. They seem to have the same symptoms of illness as the first 2 that died( shaking, unable to open thier eyes). I'm now 100% sure they had a virus and now the rest are going to die off. I feed them kaytee bricks and they live in the ovo maze and main building which has a lot of hiding spaces( stress relief) clean water, a wheel. If this keeps up I might just switch to hamsters!.