Mouse lethargic and cold

Question
Hello,

I have a male albino mouse who is about 6 months old. Yesterday he was running on his wheel and acting normal. Today was cage cleaning day (I have his brother in a separate cage and a few other animals) when I got to his cage I noticed him not moving too much (breathing still) Usually when I clean his cage he's eager to get out into his ball and run around the house, today he didnt respond the same way. He's still eating but not moving as much as he did. When I pick him up he is colder then my other mouse.
I dont keep any of my animals in the same cage (I did once for breeding but when one of my male mice killed one of the female I separated them).
I dont know if this is something behavior related since his sister died two weeks ago from Barbering herself, or is this something else?

I await your reply.


Answer
This mouse needs to see a vet. Rodents can mask illness very well as this is necessary for survival. Usually by the time they start to show illness they are very sick and need prompt vet care in order to make sure they survive. Hope the vet can help him