Headshaking syndrome causes horses to shake or flip their heads involuntarily due to trigeminal nerve pain. Often misinterpreted as behavioural, it causes significant suffering and is frequently undertreated.
Headshaking causes genuine neuropathic pain — the facial pain is often described as analogous to trigeminal neuralgia in humans, which is one of the most severe pain conditions known to medicine. Horses cannot communicate this pain verbally and often have their distress attributed to training problems or behavioural issues, leading to inappropriate handling, punishment, or prolonged periods without effective pain relief. Severe headshakers may be unable to tolerate ridden exercise at all, and attempts to work them through the condition constitute significant welfare harm. Treatment options including cyproheptadine, carbamazepine, and UV-blocking masks or nosebands can provide relief for some horses, but management is often incomplete and horses may suffer for months or years before receiving appropriate care.