Horse normally have better night vision than humans so we get use to the fact that horses lead and ride well even by moonlight. That is, unless they suffer from Night Blindness (NB). Technically known as Congenital Stationary Night Blindness (CSNB) it is a inherited disease primarily of leopard spotted Appaloosas but also seen occasionally in Tennessee Walking Horses, Paso Finos and Thoroughbreds. This article describes the causes, mode of inheritance, diagnosis, and prognosis of this eye condition of horses.

The degree of blindness varies widely from case to case. In its mildest form the horse may exhibit mild disorientation and apprehension at dusk or dark, maybe even occasionally running into objects. At its most severe horses are totally blind when the lighting is poor with increased signs of fear and running into stationary objects. Some severely effected horses are also apprehensive in bright light. Foals may stargaze in their stall at night. Occasionally there is a strabismus (deviation in the direction the eye looks) and nystagmus (regular eye tick). Important is that the degree of night blindness is non-progressive so will not worsen over time though adverse events may make a horse more apprehensive.