BLINDNESS, in farrery, is a disease incident to horses, especially those of an iron-grey or dapple-grey colour, when ridden too hard or backed too young. It may be discovered by the walk or step, which in a blind horse is always uncertain and unequal, because he dares not set down his feet boldly when led in one's hand; though if the same horse be mounted by an expert horsemanship, and the horse of himself be mettled, the fear of the spur will make him go more freely; so that his blindness can hardly be perceived. Another mark whereby a horse may be known to have lost his sight is, that upon hearing any body enter the stable, he will prick up his ears, and move them backwards and forwards, as mistrusting every thing, and being in continual alarm by the least noise. Dr. Lower first showed the cause of the ordinary blindness in horses, which is a spongy excrecence, growing in one, sometimes in two, or three places of the area, which being at length overgrown, covers the pupil when the horse is brought into the light, though in a dark stable it dilates again.