Disclosed is an in vivo equine disease model and a method of preparing the disease model for equine herpesvirus-1 neurological disease comprising a horse having a low preexposure level of herpesvirus-specific CTL precursors wherein the horse is experimentally infected with a neuropathogenic strain of equine herpesvirus or a mutant thereof. Also disclosed is a method of quantifying the risk factors and predicting the development of clinical neurologic signs of equine herpesvirus-1 neurological disease in a horse. Also described in the invention is the determination of the risk of developing the clinical neurologic signs by a mathematical equation. A new live, attenuated vaccine formulation is disclosed that is effective against neurologic disease due to equine herpesvirus-1
