Final answer:
The most common potential complication when restraining gerbils is fur slip, a defense mechanism that can cause skin exposure and health issues if not handled properly.
Step-by-step explanation:
The #1 potential complication when restraining gerbils is fur slip. Fur slip is a defense mechanism in which a gerbil will shed large amounts of fur to escape from a predator's grasp. In a captive environment, if a gerbil is restrained too tightly or handled improperly, it may experience fur slip, which can lead to skin exposure and potential health issues. It's important for handlers to be gentle and use proper techniques when restraining gerbils to avoid this complication. Other options like tail slip, nail slip, and overheating are not as common or characteristic as fur slip when discussing potential complications in restraining gerbils.