by Nancy S. Loving, DVM
In this excerpt from “The Eyes: A Horse’s View of the World” in the new book All Horse Systems Go: The Horse Owner’s Full-Color Veterinary Care and Conditioning Resource for Modern Performance, Sport and Pleasure Horses, Nancy S. Loving, DVM, explains how your horse’s eye works, and how that knowledge can help you understand your horse’s behaviour.
Spooky Behaviour
How many times have you chided a horse for spooking at an innocuous rock, or for balking at an obstacle for no apparent reason? A horse exhibits such behaviours for the same reasons that he startles when someone walks quietly up behind him in the field and he doesn’t notice until the last moment.
Just as it seems his fleeing form will vanish to the far end of the pasture, he turns, blows, and stares from a safe distance, smelling and looking to see what monster alarmed him.
Animal behaviour is predicated upon how they view the world, which senses are most operational, along with experiences gained through a lifetime. As humans peering out at the world around us, we take a lot for granted.
Even people who need glasses to correct eyesight visually enjoy a world of fantastic depth and complexity. While standing on a mountain peak casting a gaze into an endless valley, a human can pick out objects far in the distance and visually resolve them into a definite form.
Human eyes are set close together centrally on the head. This allows for binocular vision: images from each eye superimpose perfectly on one another. This “message” is relayed to the brain so that the information is not interpreted as confusing double vision.
As riders upon a horse’s back, the entire world around us is perceived as a clear picture, with objects assuming definite form and sense. What is it that a horse sees that causes him to swivel his neck and head in question, or to spook at fantasy monsters?
A Horse’s Focus and Perception
A horse raises his head to best focus on far away objects. By lowering the head, nearby objects are better focused. With each change in head position, the focal length of a horse’s eyes is adjusted to form a sharp picture on the retina.
A horse’s eyes are set on the sides of his head, allowing him to experience a more panoramic view than do people. Each eye sees separate things at the same time. The panoramic field of a horse encompasses 330 to 350 degrees. (A cat only enjoys a panoramic view of 5 to 20 degrees because his eyes are centrally located on his face.)
With very slight movements of the head, a horse is able to see just about everything around him, except for an area directly behind him that is obscured by his hindquarters. So, when negotiating obstacles, a rock, bush, or tree located directly behind a horse is invisible.
A horse’s binocular field of view is limited to between 30 and 70 degrees, providing him with very poor depth perception or evaluation of position. The best binocular field for a horse is viewed down his nose rather than straight ahead.
With head down, the binocular field is aimed toward the ground for grazing while the monocular fields from each single eye are able to scan the sideways environment in search of danger.
When a horse raises his head with nose pointing forward, both eyes are used to scan the horizon, giving the horse the best possible binocular field.
With head raised, lateral vision is at a minimum, but in this position, a horse sees well in front of himself and blind spots are eliminated. Elevation of the head enables a horse to focus on something that startles him or that poses a perceived danger.
One blind spot of a horse lies directly in front of him, encompassing an area comparable to the width of a horse. When a horse is “on the bit” with his head and nose in a vertical position, he is unable to see what is directly in front of him. Such a head position requires a horse to rely fully on his rider for navigation.
When ridden in collected gaits, a horse’s head is held in a stationary position and in a more erect manner than a horse would carry it, if given normal freedom. In the dressage arena or when showing in equitation classes, a lack of panoramic perception does not compromise a horse’s safety, especially when rails or walls confine the limits of a horse’s athletic world.
Yet with head and neck so restricted, a horse may have difficulty compensating for changes in terrain on the trail or on a cross-country course. Allowing a horse more freedom with his neck and head while negotiating trails, cutting cows, or while jumping gives a horse better vision and elicits more confidence and ability. By rotating the head a bit to either side, a horse is able to amplify his visual perception to the side and immediately behind him.
Besides the blind spots directly in front of and behind his own body, a horse cannot see directly beneath his nose. A horse is unable to distinguish anything placed less than four feet in front of him, including what he eats. For food discrimination, he relies on keen senses of smell and taste. But for negotiating obstacles, he relies upon his vision.
As a horse approaches a jump or a tree-fall across a trail, he must have had a good view and measure of the obstacle before it is directly upon him. If he can’t see it from afar, an obstacle may scare him and cause him to balk when asked to proceed forward. If it is a jump that comes upon him suddenly, he may refuse, run-out, or attempt a dangerous leap that could result in a fall.
In addition to the fact that a horse cannot see less than four feet in front of him, his face and nose obscure his line of sight. A horse cannot clearly see objects above the level of his eyes, so he may raise his head to get a better look. This poses a compromise in vision since a horse that holds his head high cannot see the ground in front of him.
Because equine eyes are set out to the side, one eye may see an object before the other does. Accordingly, when the other eye catches on the object, even a stationary rock may seem to “jump” at the horse. (Rapid blinking of your alternate eyes simulates such a “jumping” image, as a horse would see it.)
Imagine what a horse must see when a bright, white rock suddenly appears around the bend in the trail. This explains why there seem to be fantasy monsters lurking behind a rock, a tree, or why a piece of plastic becomes an object of terror.
Survival instincts tell horses to stay clear of such dangers; this results in reactive shying at inconvenient times. Man has developed blinders to prevent a horse from being distracted by movements around him so he better concentrates on where he is going.
How to Apply Vision Principles to Riding
One of the more challenging things a horse person has to accomplish is to encourage a horse to concentrate on the task at hand. Not only do distractions confuse a horse from his job, but also as his head, eyes, and ears swivel around to look to the side, he does not see in front of him.
Such lapse in attention results in jerky and weaving movement, and a horse may lose concentration and fail to negotiate a tricky section of terrain.
As he throws his head in the air to “look” at his world from another vantage he may knock down or trip over an obstacle that normally he would have stepped over gracefully. Or, he may balk and stop, or altogether spin away, returning in the direction from which he came. He may trip and stumble, putting him at risk of injury from a misstep.
In varied equine sport disciplines, lapses in attention could cause a horse to lose a selected cow, refuse a jump, or slow down in speed; in effect he loses the winning edge.
By holding the biologic phenomenon of the equine eye in our minds, we can better predict what might startle or scare our mounts. Providing good experiences boosts a horse’s confidence, and builds a horse’s trust in his rider. “Listening” to a horse’s body posture tells volumes of information about his insecurities.
By looking at the world through a horse-eye view, quirks of equine behaviour become more understandable and more predictable. Many images that a horse perceives as confused and jumbled can be translated for him with a simple word or a steadying hand on his neck, turning it into a non-frightening situation.
A scary rock or puddle, an alarming jump, or distracting crowds may melt into obscurity with steadying pressure of a rider’s legs, seat, and hands to focus a horse’s attention on the task at hand.
To order your own copy of All Horse Systems Go: The Horse Owner’s Full-Color Veterinary Care and Conditioning Resource for Modern Performance, Sport and Pleasure Horses, turn –to this month’s Book Barn on page 81. Reprinted by permission from Trafalgar Square Books, www. horseandriderbooks.com.
