Trigeminal-mediated headshaking: A diagnostic challenge

The term 'equine trigeminal-mediated headshaking' (TMHS) has replaced the previously used diagnosis of ‘idiopathic headshaking’ to reflect the clinical signs, which are considered to characterise trigeminal neuropathic pain (Pickles et al., 2014). This diagnosis is reserved for horses with a presumed functional, rather than structural, disorder of the trigeminal nerve, as distinct from horses such as those described in the case series by Ogden et al. (2022) where gross pathology, in this case trauma of trigeminal nerve branches, induces clinical signs of headshaking