Hello,
Your gerbil is a senior citizen and this very well may be a stroke. If this is the case he may or may not recovery fully.The key now is to be sure he is taking fluids and able to eat. You can try using plain Pedialyte instead of water as this will replace the electrolytes in the body. You may need to grind the food and dilute it to syringe feed it. I suggest Oxbow critical care for herbivores. Keep him as quiet as possible and make sure his temperture is staying steady. Joan
This link speaks about different Gerbil illnessed and explains about strokes in Gerbils:
http://www.gerbils.co.uk/gerbils/ailments.htm
Veterinary Technician
I am Vet Tech. for 30+yrs. who works with all animals. I do alot of rescue work with small animals.