[header] How to diagnose respiratory problems in gerbils [title] Examine your gerbil's eyes and nose. [step] When a gerbil has a respiratory problem, a liquid discharge will start coming out of its eyes and nose. This discharge may be thick and mucus-like, indicating an infection. 
[substeps] Your gerbil's eyes may also be half closed and look dull. A healthy gerbil's eyes would be fully open and bright with an alert-looking stare.