hello! One of my rats has recently had a very soft whistle when he runs around, I’m not sure if it is his lungs or nose. The room they are in can get a bit dry in the winter and the cage is on the floor so I lifted them up higher in case dust is irritating him and will put a humidifier to help. They always have a clean cage so that wouldn’t be an issue. He’s never sneezed or had any breathing problems before and still has never sneezed. If it doesn’t go away I will definitely bring him to the vet. Do you think he has a stuffed nose or is it a lung problem? Has anyone ever had a rat with a nose whistle or is it a clear sign of a lung infection, it’s very mild. I also bought them new toys made for rats and he really chewed on that so maybe he even has something lodged in there, I gave him peas with water to try and see if that washes it out.