If your gerbil starts to tip over to one side starting with their head this can be a sign of a middle ear infection. This can also be a sign of brain tumours or a stroke but this is a lot less common and your vet will be able to tell you what is the problems. Flu and Respiratory Infections. If your gerbil appears to be having problems with breathing, particularly if you can hear clicking or squeaking sounds, take him straight down the vet. It may be a sign of a more serious problem such as lung tumours in older animals but this is less likely than an infection.
Gerbils can also catch flu.
This is very nasty indeed and we had an outbreak last winter. If your pet looks obviously ill and is wet around the mouth then get him straight down the vet. The treatment is daily baytril injects to prevent secondary infections setting in and to keep your pet as warm and hydrated as possible. If it is winter get a heater to run in the room over night. You may need to move the water bottle so that the animal can get to it easily or even hand feed water with a pipette.