I did some research and Neurontin can be prescribed for birds with ABV, PDD and mutilation. It helps control the pain on the nerve endings of the body. However, it is warned that blood tests to check for liver and renal function should be done prior to administering and while on it if long term as it can cause a decrease in their functions.
"5) Gabapentin (Neurontin®): Birds that exhibit seizure activity or evidence of nerve-related pain (i.e. feather damaging/mutilation) may benefit from this medication. Other methods of pain control may be required based upon patient response.