Development of a noninvasive video-oculography setup for determining VOR presence in a severe vestibular impairment mouse model

The vestibulo-ocular reflex (VOR), which stabilizes gaze during head movement, serves as a key indicator of vestibular integrity. Conventional systems for VOR measurement in mice often require invasive head fixation, posing risks to animal welfare and experimental reproducibility. In this study, we developed and validated a noninvasive immobilization setup for detecting the presence of VOR responses in a severe vestibular impairment mouse model, offering a welfare-oriented alternative to surgically fixed systems. Using video-oculography (VOG), we assessed VOR responses in control and vestibular-impaired CD-1 mice, with vestibular dysfunction induced via oral administration of the ototoxic compound allylnitrile. As expected, allylnitrile-treated mice exhibited a near-complete absence of VOR responses, confirming profound vestibular impairment. Complementary assessments included Vestibular Dysfunction Index (VDI) scoring, swimming tests, immunofluorescent staining for hair cell counts in vestibular cristae and hearing tests. Because the induced, severe deficits precluded quantitative gain and phase analysis in this study, the set-up is currently limited to binary VOR detection in this model. However, further research will determine if under conditions of partial or progressive impairment, this noninvasive system supports more detailed characterization of VOR dynamics. Overall, the optimized, surgery-free setup demonstrated here enhances the reproducibility and welfare standards of vestibular testing in mice, offering a refined platform for detecting VOR presence in a severe vestibular impairment mouse model.