Management of Blindness in Horses

Take Home Message  

Blindness is a common end result of equine uveitis. Today, many horses that go blind are not  euthanized, but are kept as pets, companions, and occasionally as riding horses. Practitioners  must know how to counsel owners of horses who are blind or have a poor visual prognosis. This  paper presents basic facts about blind horse behavior and adaptation to vision loss. Tips on enucleation of painful blind eyes are included. Resources that will be helpful for horse owners  are listed.  

Causes of Blindness in Horses  

Uveitis is the leading cause of blindness in horses. Some horses suffering from uveitis have  recurrent episodes of acute inflammation interspersed with quiet periods; others (mainly  Appaloosas and draft horses) have slow degeneration of the ocular structures due to insidious but  persistent disease. At least 50% of equine eyes that are affected with uveitis have been observed by the author to eventually lose vision, despite intense treatment of acute episodes and careful  management of insidious cases.¹ The actual cause of vision loss in uveitic horses varies: some  horses develop dense cataracts, some go blind from the consequences of secondary glaucoma,  some horses develop detached retinas and others go on to suffer degeneration of the ciliary body  and become phthisical.  

Many other diseases cause blindness. Severely infected or melting corneal ulcers may fail to  respond to therapy and progress to the point where enucleation is necessary. Penetrating injuries  can occur that cause internal scarring or globe rupture. Neoplasia can occur on the globe, adnexa  or in the orbit, necessitating enucleation. Severe head injuries can cause intracranial damage that  result in cortical blindness. Occasionally horses are born blind with congenital conditions like  microphthalmos. No statistics have been compiled to document the incidence of blindness in  horses worldwide but it is significant. Unilateral blindness is quite common, affecting perhaps as  many as 1-2% of the general population.^a Bilateral blindness is less common but still affects a  large group of horses.  

Recent changes in attitudes on animal welfare have changed the management of many blind  horses. In the past, most bilateral blind horses were subject to euthanasia either at  slaughterhouses or at home farms. Now, many people choose to maintain blind horses as pets  and companions. Some blind horses are ridden and a few compete in athletic events like dressage  or reining.  

Adaptation to Acquired Blindness

Most horses lose vision gradually. As acuity decreases, handlers may notice progressive  uncertainty, especially in low light situations. Herd behavior may change. Riders may report  frequent shying or balking. Certain low light conditions may be accompanied by instances where  the horse is observed bumping into obstacles.  

When complete blindness occurs, some horses go through a period of fear or anxiety. Handlers may report episodes of rapid circling, freezing in place, prolonged neighing and spooking. A  previously tractable horse may become dangerous to be around if it crashes into a wall or runs  over a handler. The horse may initially be observed to show a head tilt or walk slightly off  balance. Other individuals show a calmer acceptance of blindness but are still at risk for injuring  themselves or others if they run into something.  

Horses with reasonable temperaments adjust to blindness after an adaption period of several  weeks. Horses who are good candidates for adjusting to blindness are those with calm, easy  going temperaments and dedicated owners who are willing to make environmental and  management changes that accommodate the disability. Owners of horses with vision loss should  always allow the horse a “transition period” of several days to weeks to adjust to blindness  before judging what the long term temperament will be.  

Some horses with high strung, nervous temperaments never adjust well to vision loss and pose a  constant risk of injury to themselves or their handlers. Horses that are have nervous  temperaments and are owned by owners who are not dedicated to their long term management  may need to be euthanized.  

Social Interactions with Other Horses 

Some horses benefit from the presence of a calm, sighted companion in their paddock or barn in the period where they are adjusting to blindness. Others fare better if they are kept alone.  

Once the adjustment to blindness has been made, most blind horses enjoy the company of one  gentle, compatible companion. This can be another horse, a pony, or a goat. The bond that develops between the “pasture buddies” may become extremely close. The sighted horse may  serve as a “seeing eye” for the blind one. Sometimes the sighted animal may even be observed to  “lead” the blind horse around obstacles. Handlers should be aware that the bond between these  pasture companions will be exceptionally strong. If one horse has to be separated from the other,  both may display extreme anxiety. However, blind horses that lose their “pasture buddy” will  generally adjust quickly to a replacement companion.^b  

Blind horses generally do not fare well in herds. Herd interactions generally revolve around a  social hierarchy and a blind horse will move to the bottom of the pecking order. Blind horses in  herds are typically pushed around, treated as outcasts and not allowed choice access to food, so they generally fail to thrive. 

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