A German study raises troubling questions about the impact of trigeminal-mediated headshaking (TMHS) on horses.
TMHS occurs when, for reasons still unknown, the trigeminal nerve, which runs along the front of a horse’s face, becomes overly sensitive. InhorseswithTMHS, mild stimuli like sunlight, wind, touch or even noise can trigger severe pain. The most common response to this pain is a distinctive and repetitive nose-flicking “head toss”; other signs include snorting, nose-rubbing and lip movement. Even mild TMHS can make a horse difficult to ride, and a severe case can render him unsafe to handle at all.
Despite decades of research, “we still don’t know the actual cause of TMHS,” says Professor Anna May, DVM, of Ludwig Maximilians University in Munich, Germany. “It can be due to an injury or other…