A dog bite to the head of a gerbil is a serious injury. It is extremely unlikely that a gerbil would survive such an attack. Gerbils are very fragile creatures, and a dog bite to the head would likely cause severe trauma, including potential skull fractures, brain damage, and internal bleeding.
If you are concerned about a gerbil that has been bitten by a dog, please contact a veterinarian immediately.
It is important to keep pets separate and supervise any interactions between dogs and gerbils.