Nor could they slam on the brakes and come to an impressive sliding stop inches from an obstacle. They certainly wouldn't be able to “lock onto” and cut cattle, run barrels, or do any of the thousand of things we ask horses to do.
Changing Perceptions Myths start when someone introduces a training technique based on a theory about horse vision. Think about the astonished third-grader who struggles in school until he puts on a pair of glasses and suddenly sees the blackboard clearly for the very first time.
We set up carefully controlled experiments to eliminate the red herrings that so easily confuse us. “There are quite a few myths and misconceptions about how horses see,” agrees Dr. Evelyn Hang, president of the Equine Research Foundation in Autos, California.
“After repeatedly reading and hearing odd things about equine vision, we decided to design some noninvasive studies that would provide solid evidence one way or another.” • Because of the way horses eyes are positioned, they have small blind spots directly in front of and behind them when their heads and necks are straight.
• Allowing your horse to raise, lower or tilt his head can help him judge distances better when jumping, cutting, running or working obstacles. • Areas of high contrast may initially startle or worry horses, but their eyes quickly adjust to differences in brightness and shadow.
Peripheral Vision Like most open-space prey animals, the horse's eyes are placed predominantly on the sides of their heads. However, horses do have a small blind spot in front of their noses, and another just behind their tails, and they probably cannot see much that is sitting low on their backs either.
And this ability to see different things out of each eye helps the horse assimilate what's going on around him in a generalized way. Using “binocular” vision, in which both eyes work together, horses can zero in on a selected point or object, such as that trail obstacle we're asking them to negotiate, or the cow we want to track.
This misguided theory suggests that the two sides of the horse's brain are neither connected nor communicating. This, as Dr. Hang notes, would make the horse quite bizarre in the animal kingdom because, like nearly every other mammal, horses have a structure in the brain called the corpus callosum that connects both hemispheres of the brain, so information is shared back and forth.
Since just the presence of this bit of anatomy doesn't prove information actually gets transferred, Dr. Hang ran a series of tests using images the horses had never seen before. With no humans around to give inadvertent signals, the horses were given a choice of pictures to touch with their noses to receive food rewards.
To test the eye-to-eye myth, the Equine Research Foundation horses were trained to respond to one of two choices while one eye was blindfolded. Dr. Hang did experiments on this issue and determined that horses actually can recognize rotated objects from most (but not all) orientations.
Horses who have seen many objects in different situations and have developed trust in their riders generally react more calmly when confronted with just one more oddity. There could be a critter rustling in the grass, or a broken hinge that gives it a very different outline than it had an hour before.
As far as creeks, rocks, bushes, trees or the neighbor's barn are concerned, it might help to remember that just as an experienced hiker or trail rider will regularly look behind him to try to stay oriented-knowing that landmarks can be unrecognizable when seen from the opposite direction on the way home-it is possible that the horse may not recognize a potentially scary object from the opposite direction either, so he honestly needs to investigate it all over again to convince himself it's not a horse-eating monster. First, viewing objects with just one eye does provide an adequate degree of depth perception.
One way horses seem to refine their depth perception is to raise, lower and/or tilt their heads. One practical training application to this is, if you are asking your horse to jump, cut, or maneuver closely around or through something, he is going to find it a lot easier if he has a fairly loose rein and/or the freedom to move his head, so he can judge distances.
That relatively small blind spot in front of the horse's nose, however, has some major, practical implications for riders. The peripheral vision is still showing what is to the side, but he is working blind in regard to anything smack dab in front of him.
It's a persuasive argument for riders to look up and ahead, not down at the horse's neck, since at least one member of the horse/rider combination has to see what's coming up! It might also explain why some horses are uneasy or resist being asked to comply with an unnatural headset.
The horses were trained to choose between pictures of vertical black and white stripes of different widths. Researchers kept narrowing the width of the stripes until the horses showed they could no longer detect a difference.
Perfect human vision is considered to be 20/20, so your horse could probably pass a drivers' license eye exam. Horses eyes seem fairly sensitive to low light, and they can see reasonably well at night.
Dr. Hang, who is conducting experiments regarding the horse's night vision, relates a good example of this. “I was in the high desert with ERF program director Jerry Ingersoll on our annual trip to observe wild Mustangs.
Within a minute, a large band of Mustangs came galloping right past our tent-in the dark, through rough terrain made up of hills, gullies, rocks and sagebrush. Also, notable is that horses can adjust to major differences in brightness and shadow fairly quickly, but specific situations may affect their reactions to a great degree.
The reason your horse might hesitate at entering a darkened doorway or be “look” at a log on the trail as you are passing from a bright field into darker trees might be because he can't see right away what he's being asked to go into or over. This means a horse can see movement in most areas around its body, even with its head facing forward.
The eye is an active organ that constantly adjusts the amount of light it lets in and focuses on objects near and far. The orbit also contains muscles, nerves, blood vessels, and the structures that produce and drain tears.
It is covered by a thin membrane, called the conjunctiva, located near the front of the eye. The conjunctiva runs to the edge of the cornea and covers the inside of the eyelid.
The cornea is a clear dome on the front surface of the eye that lets light in. It controls the amount of light that enters the eye by making the pupil larger or smaller.
The lens, which sits behind the iris, changes its shape to focus light onto the retina. The biliary muscles relax to cause the lens to become thinner when it focuses on distant objects.
This area contains thousands of tightly packed photoreceptors that make visual images sharp. The photoreceptors in the retina convert the image into electrical impulses, which are carried to the brain by the optic nerve.
The upper and lower eyelids are thin folds of skin that can cover the eye and reflexively blink to protect it. Blinking also helps spread tears over the surface of the eye, keeping it moist and clearing away small particles.
The third eyelid extends up when needed to protect the eyeball from scratches or in response to inflammation. The mixture of water, oil, and mucus creates a more protective tear that is slower to evaporate.
Using light and magnification in a darkened stall, the reflexes of the pupils and the front part of the eye will be examined. This is a relatively simple test in which small paper strips are inserted under the eyelid to measure the amount of moisture produced.
Pressure within the eye is painlessly measured using an instrument called a odometer. If eye pressure is too high, optic nerve damage can occur, leading to irreversible blindness.
Many people think that animals, including horses, are colorblind and only see in shades of gray. If you've ever called your horses in from a pasture in the dark, you'll no doubt have been surprised as they barreled towards you at a wild gallop, but arrived without stumbling over rough ground.
This is caused by the tape tum lucid um, a membrane at the back of the eye that reflects light and also aids their night vision. Conditions that would leave us groping for the light switch or flashlight are less worrisome for a horse.
If you've ever walked into the barn at night and flipped the light on suddenly, you'll probably have noticed that the horses blink for quite a long time afterward. As prey animals, horses vision played an essential role in being able to see predators and take flight before they ended up as dinner.
Since a horse has difficulty seeing things directly in front of them, when they are negotiating jumps, a narrow bridge, or other obstacles, they may briefly be doing it while effectively blind. Appaloosas, Paints, Pintos, and other horses with lots of white on their faces will sometimes have blue eyes.
The protective layer in the corner of a horse’s eye, called the initiating membrane, helps prevent irritation from dust and objects like grass seeds and stems. You'll often see a bit of tearing and grime in this area that can be wiped away with a soft damp sponge or cloth as part of your grooming routine.
It's important to understand how they perceive the world, why they react the way they do to shadows and changes in light, and the extent of their close-up and distance vision. Editor’s Note: This article was revised by the author to reflect new and updated information in November 2017.
While vision in only one eye does not mean the horse must be euthanized, it does somewhat limit the athletic and working potential of that animal. This article discusses the anatomy and physiology of the eye, complete with drawings and photographs.
Respiratory sinuses border the horse orbit on the midline (center of the head). Eyelid swelling can be an early sign of corneal ulceration (more about corneas in a moment).
Magician glands, which secrete the fatty component of the tear film that lubricates the eye, are found at the eyelid margins. Horses have large eyelashes or cilia on their upper eyelid margin and none on the lower lid.
It has supportive cartilage and a covering of conjunctiva (the same delicate membrane that lines the eyelids). Components of the immune system that protect the eye and tear-producing cells are present in the conjunctiva, which is pigmented near the limbs (more on this later) in some horses.
The tear film layer, cornea, iridocorneal angle, iris, lens, and biliary body comprise the anterior (forward) segment of the eye. Tears enter the tear drainage system at the medial acanthus (pocket formed at the inside of the eye), pass through the bony nasolacrimal duct in the skull, and drain in the horse’s nose.
Light rays pass through the cornea to begin the visual process and are focused on the retina. The stoma constitutes approximately 90% of the corneal thickness and is mostly collagen (a fibrous protein).
The innermost endothelium consists of only one cell layer, but it contains a little pump that drains water out of the cornea so it stays clear. Endothelial disease results in pump failure and corneal swelling.
In most horses, there is an obvious gray line at the limbs where ligaments bridging the iris and cornea are visible. The sclera is connected to the cornea and constitutes the major portion of the outer layer of the eyeball.
It is observed as a thick gray band on the nasal and temporal regions of the limbs. Aqueous humor is a clear fluid derived from blood that aids corneal and lens health.
Horses have cystic granular iridium or corpora nigga that appear to hang from the top of the papillary rim; they are believed to shield the retina from overhead sunlight. During uveitis, the iris sphincter muscle contracts to cause profound closing of the pupil.
The biliary body muscles spasm, resulting in severe ocular pain and squinting. The capillaries (small blood vessels) in the veal tissue become leaky and release proteins and cells during attacks of uveitis.
The lens is a transparent structure located behind the iris and held in place by popular ligaments. The retina also contains a high number of very large ganglion cells that conduct the visual impulses quickly, which explains the superb ability of horses to detect movement in their field of vision.
Brooks DE: “Equine Ophthalmology-Made Easy- edition, TetonNewMedia, Jackson Hole, WY, 2008. Wiley-Blackwell, Ames, IA, 2008 Ginger BC: Equine Ophthalmology, 3rd Edition.
Both the strengths and weaknesses of the horse's visual abilities should be taken into consideration when training the animal, as an understanding of the horse's eye can help to discover why the animal behaves the way it does in various situations. The equine eye includes the eyeball and the surrounding muscles and structures, termed the adnexa.
The eyeball of the horse is not perfectly spherical, but rather is flattened anterior to posterior. The nervous tunic (or retina) is made up of cells which are extensions of the brain, coming off the optic nerve.
These receptors are light-sensitive, and include cones, which are less light-sensitive, but allow the eye to see color and provide visual acuity, and rod cells, which are more light-sensitive, providing night vision, but only seeing light and dark differences. Since only two-thirds of the eye can receive light, the receptor cells do not need to cover the entire interior of the eye, and line only the area from pupil to the optic disk.
The vascular tunic (or UVA) is made up of the choroid, the biliary body, and the iris. The choroid has a great deal of pigment, and is almost entirely made of blood vessels.
The tape tum lucid um reflects light back onto the retina, allowing for greater absorption in dark conditions. The iris lies between the cornea and the lens, and not only gives the eye its color, (see “eye color,” below) but also allows varying amounts of light to pass through its center hole, the pupil.
The fibrous tunic consists of the sclera and cornea and protects the eye. The sclera (white of the eye) is made up of elastin and collagen.
The cornea (clear covering on the front of the eye) is made up of connective tissue and bathed in lachrymal fluid and aqueous humor, which provides it nutrition, as it does not have access to blood vessels. The lens of the eye lies posterior to the iris, and is held suspended by the biliary suspension ligament and the biliary muscle, which allows for “accommodation” of the eye: it allows the lens to change shape to focus on different objects.
Eye color Homozygous cream dilutes (“double-dilutes”) have pale blue eyes, while the blue eyes associated with white markings (bottom) are a clearer, deeper color. Although usually dark brown, the iris may be a variety of colors, including blue, hazel, amber, and green. Blue eyes are not uncommon and are associated with white markings or patterns.
The adnexa of the eye, including the third eyelid (seen in the left corner)The eyelids are made up of three layers of tissue: a thin layer of skin, which is covered in hair, a layer of muscles which allow the lid to open and close, and the algebra conjunctiva, which lies against the eyeball. Unlike humans, horses also have a third eyelid (initiating membrane) to protect the cornea.
It lies on the inside corner of the eye, and closes diagonally over it. The lachrymal apparatus produces tears, providing nutrition and moisture to the eye, as well as helping to remove any debris that may have entered.
The ocular muscles allow the eye to move within the skull. The range of a horse's monocular vision, blind spots are in shaded areas horse can use binocular vision to focus on distant objects by raising its head. A horse with the head held vertically will have binocular focus on objects near its feet.
The horse's wide range of monocular vision has two “blind spots,” or areas where the animal cannot see: in front of the face, making a cone that comes to a point at about 90–120 cm (3–4 ft) in front of the horse, and right behind its head, which extends over the back and behind the tail when standing with the head facing straight forward. The wide range of monocular vision has a trade-off: The placement of the horse's eyes decreases the possible range of binocular vision to around 65° on a horizontal plane, occurring in a triangular shape primarily in front of the horse's face.
The horse uses its binocular vision by looking straight at an object, raising its head when it looks at a distant predator or focuses on an obstacle to jump. To use binocular vision on a closer object near the ground, such as a snake or threat to its feet, the horse drops its nose and looks downward with its neck somewhat arched.
A horse will raise or lower its head to increase its range of binocular vision. A horse's visual field is lowered when it is asked to go “on the bit” with the head held perpendicular to the ground.
This makes the horse's binocular vision focus less on distant objects and more on the immediate ground in front of the horse, suitable for arena distances, but less adaptive to a cross-country setting. Riders who ride with their horses “deep”, “behind the vertical”, or in a roller frame decrease the range of the horse's distance vision even more, focusing only a few feet ahead of the front feet.
Riders of jumpers take their horses use of distance vision into consideration, allowing their horses to raise their heads a few strides before a jump, so the animals are able to assess the jumps and the proper take-off spots. The horse has a “visual streak”, or an area within the retina, linear, with a high concentration of ganglion cells (up to 6100 cells/mm 2 in the visual streak compared to the 150 and 200 cells/mm 2 in the peripheral area).
They therefore will tilt or raise their heads, to help place the objects within the area of the visual streak. Such motion is usually first detected in their periphery, where they have poor visual acuity, and horses will usually act defensive and run if something suddenly moves into their peripheral field of vision.
A representation of how a horse possibly sees a red or a green apple (bottom) compared to how red or green apples are usually seen by most humans (top) Horses are not color-blind, they have two-color, or chromatic vision. This means they distinguish colors in two wavelength regions of visible light, compared to the three-color (dichroic vision) of most humans.
This structure may have arisen because horses are most active at dawn and dusk, a time when the rods of the eye are especially useful. The horse's limited ability to see color is sometimes taken into consideration when designing obstacles for the horse to jump, since the animal will have a harder time distinguishing between the obstacle and the ground if the two are only a few shades different.
Therefore, most people paint their jump rails a different color from the footing or the surrounding landscape so that the horse may better judge the obstacle on the approach. Mare and foal with eye shine from the tape tum lucid um Horses have more rods than humans, a high proportion of rods to cones (about 20:1), as well as a tape tum lucid um, giving them superior night vision.
The large eye of the horse improves achromatic tasks, particularly in dim conditions, which presumably assists in the detection of predators. Laboratory studies show horses are able to distinguish different shapes in low light, including levels mimicking dark, moonless nights in wooded areas.
When light decreases to nearly dark, horses can not discriminate between different shapes, but remain able to negotiate around the enclosure and testing equipment in conditions where humans in the same enclosure “stumbled into walls, apparatus, pylons, and even the horse itself.” However, horses are less able to adjust to sudden changes of light than are humans, such as when moving from a bright day into a dark barn.
This is a consideration during training, as certain tasks, such as loading into a trailer, may frighten a horse simply because it cannot see adequately. It is also important in riding, as quickly moving from light to dark or vice versa will temporarily make it difficult for the animal to judge what is in front of it.
Horses have relatively poor “accommodation” (change focus, done by changing the shape of the lens, to sharply see objects near and far), as they have weak biliary muscles. However, this does not usually place them at a disadvantage, as accommodation is often used when focusing with high acuity on things up close, and horses rarely need to do so.
It has been thought that, instead, the horse often tilts its head slightly to focus on things without the benefit of a high degree of accommodation, however more recent evidence shows that the head movements are linked to the horse's use of its binocular field rather than to focus requirements. Clinical signs of injury or disease include swelling, redness, and abnormal discharge.
Illustrated Atlas of Clinical Equine Anatomy and Common Disorders of the Horse Vol. Australian Equine Genetics Research Center, web page accessed July 20, 2007, at http://www.aegrc.uq.edu.au/index.html?page=30056 Archived 2007-08-29 at the Payback Machine ^ Locke, MM; LS Ruth; LV Million; MCT Opened; JC Murray; AT Bowling (2001).
“The cream dilution gene, responsible for the palomino and buckskin coat colors, maps to horse chromosome 21”. The eyes and skin of palominos and buckskins are often slightly lighter than their non-dilute equivalents.
^ Herman AM, Moore S, Hopkins R, Keller P. Horse vision and the explanation of visual behavior originally explained by the ‘ramp retina’. ^ “Shedding Light on Equine Night Vision” The Horse online edition, October 12, 2009 ^ Griffin, James M and Tom Gore.
The sliver changes in size and shape with the sun’s movement, and the mare seems to see each tiny difference as a brand-new snake. These are normal behaviors that reflect the way a horse’s visual systems are hardwired into his brain.
How we respond to his fear depends partly on our own vision, which determines our expectations of what horses see. Since the 1960s, cognitive psychologists have shown that we construct sight using information from our eyes combined with knowledge in our brains.
One whose eyes are intact but whose visual cortex is damaged often sees lights and shadows but can’t make sense of them. In rare cases, people who are completely brain-blind can grasp a coffee cup set in front of them or navigate around objects, responding to the physical world even though they cannot consciously see it.
This ability, called “blind sight,” isn’t limited to humans; critically blind animals can do it, too. Occasionally, a smidgen of visual cortex is impaired so specifically that its owner---having otherwise normal sight---suddenly cannot see color, shape or perhaps movement.
Imagine trying to cross a busy street with eyes that function normally but a brain that can’t perceive motion. Cars travelling 60 miles an hour become a series of still images stopped along the road.
But the human brain sends back six times as much neural information in the opposite direction, transmitting messages to the sensory relay station that captures incoming views. This wiring is infrastructure for perceptual interpretation: the effect of knowledge being melded with the eye’s pictures of the outside world.
If you want to shape your horse’s performance and gain his trust, you need to understand how his vision differs from yours. You can then use that understanding to develop training techniques that work with the horse’s visual system instead of against it.
Walking in an open field as a bird flicks a wing in the distance, a horse may raise his head, point his ears, flare his nostrils and widen his eyes. This impressive display of intelligence and sensitivity is sometimes called the “look of eagles.” But it stems from how equine vision works.
Focusing on the bird’s location, the horse is trying to improve his view by raising his head and enlarging his eyes. But a horse’s acuity---the ability to discriminate fine detail while focusing on something in the center of the visual field---is considerably worse than ours.
But equestrians are often startled to see photographs constructed to show what a jump looks like to a horse. Even in sunshine, the horse’s view of a jump is blurry, hazy, dim, flat, vague … all the adjectives you’d rather not ponder as you’re galloping 30 feet per second toward a big over that could ruin your day.
It stands to reason that slightly far-sighted horses will excel in disciplines like jumping where the ability to home in on fine points from a distance fuels their athleticism. The most obvious features of a horse’s eyes are their size and placement on the sides of the head.
The position of the eyes on the face accounts for profound differences in the ways people and horses see, dictating visual range, peripheral motion detection and depth perception. Trendy tie-downs and personality assessments won’t change that---we have to accept how horses see the world and work with it.
Human sight is accurate enough to decode tiny marks on a page, but only for a small slice of the view. Stretch your arm full length to your side, holding up your index finger.
By contrast, if your horse could hold his hind hoof straight out to his side, it would be almost in the center of his vision. Because his eyes are on the sides of his head, he has a 350-degree view, almost four times greater than the range we see.
The horse’s visual range stretches from the end of his nose all the way around to an imaginary line extending straight back from his hip. The balloon bobbing at the side of the arena is the equivalent of a ball soaring straight toward a horse’s face.
The horse sees a broad band of the world to the sides and back of his body, but it is narrow. Sights directly to the horse’s side but on the ground or in the air are difficult to see unless he cocks his head.
A second blind spot exists in front of the horse’s face, from his eye level to the ground below his nose and out to about six feet. He cannot see the grass he grazes on, the bit he accepts, the fingers that stroke his muzzle.
One of the most common mistakes people make when dealing with nervous horses is to thwart their side view. The rider, with forward facing eyes, assumes that positioning a horse for a frontal view is best for all.
The rider pushes Hawkeye straight toward the sliver of light on the sand that already scares the believers out of her, then tries to make her stand still and stare at it head on, eyes bugged out like tennis balls. All Hawkeye knows is that her rider is upset, forcing her forward to a place that she considers threatening.
Second, as she reluctantly approaches, the light-snake vanishes from Hawkeye’s line of sight, which of course makes it all the more frightening. Fourth, when Hawkeye cocks her head and pivots to the side for a better view, her rider pulls on one rein and presses with the opposite leg, pushing her back to a stance where equine vision is worst.
We might think it silly that Hawkeye is afraid of flapping plastic or a paper cup … but how would you feel about having a big, hairy tarantula running through your hair? Then use some vicarious learning: Let Hawkeye watch a familiar human friend walk to the object, stand next to it and speak calmly.
Speak slowly in a low pitch and stroke your horse’s neck while she watches her buddy survive the terror. If this also fails, move out of sight of the object and put your horse to work on a completely unrelated task.
When your horse is relaxed while viewing the threat, even if only from a distance, walk her back and forth past the object before requesting a head-on approach. Touch the hazard so your hand makes a soft noise against it; this will allow the horse to learn more through her excellent hearing.
It’s tempting to call it a day and drive to the nearest ice cream store for solace. When Hawkeye is calm, quietly enlarge the loops, maintaining any distance that allows her to remain tranquil.
Forcing a horse is a good way to destroy her trust in you, frighten her all the more, and wake up with Nurse Matched by your bed. Prey animals identify predators by smell and sight---including their view of eye position.
Because horses see us as natural predators, human eye contact has a warning effect. If your horse moves too quickly on a long line or in a round pen, try looking down, watching and listening to his feet surreptitiously to stay safe.
To move in for a kill, predators need sharp sight in central areas of the visual field. In other words, horses must notice peripheral motion immediately, regardless of what it is, so they can leave the scene at high speed before a potential predator begins to approach.
When needed, equine eyes can even move independently to scan one side of their world more intently than the other. The human brain takes half a second to process each glance at the world and determine what it has seen---shape, color, size, distance, importance and so on.
Half a second of processing is out of the question for a horse in the wild: He needs to notice a tiny movement in the bushes and step on the gas. The horse’s natural reliance on peripheral motion detection dictates his need to shy or bolt---and otherwise “misbehave”---while ridden.
Try to become more aware of objects behind and to the sides of your eye, putting your ears, nose and cognitive experience to work. Acuity, range, eye contact and peripheral motion detection---in all these ways the horse’s vision differs from a person’s.
Keeping these differences in mind will help you to communicate more effectively with your horse and train him in ways that accommodate his senses. About the author: Janet L. Jones earned her PhD in cognitive science, the study of the human mind and brain.
Now professor emerita, she has taught the psychology and neuroscience of memory, language, perception and thought for 23 years and is the author of three books. She has competed in Western, English, reining, hunter and jumper classes in five states and uses the principles of dressage with every horse.
Within a few strides of the obstacle, the rider tenses slightly; the horse rocks his weight back over his hindquarters in preparation for takeoff. The equine eye is designed to help horses easily spot predators, footing, and food.
Odds are, if you saw what he saw on his approach to the fence (or what your own horse will see when he jumps a ditch or a fallen log, or crosses a trail obstacle), you’d stop, too. If you do anything to rattle that faith, as the rider in the above scenario did (by tensing up), chances are, your horse won’t take the leap.
By the end of our ride, you’ll find that viewing the world through your horse’s eyes will open a window to equine behavior. You’ll have a better understanding of why your horse spooks at “invisible” demons; why objects that look harmless to you send him flying sideways; and why he often reacts to things as though he’s viewing them for the first time, even though you know he’s seen them before.
In preparation for our ride, I opened the aluminum gate earlier; you see it propped up on the grass beside my driveway, shimmering in the bright sun. This phenomenon, known as binocular vision, is indigenous to predators, which, like cats, dogs, cougars, wolves, etc., we humans are.
Nature designed binocular vision to enable predators to chase down, catch, and kill prey darting in front of them. Your eyes automatically focus on the gate, using flexible disc-like lenses that are attached to powerful biliary muscles.
Why he sees it that way: Your horse’s eyeball is the largest orb found in any land mammal, and has a correspondingly oversized retina. What you see: As we top a slight hill, you spot a couple of white-tail deer 50 yards below and to your left, grazing in front of a stand of trees.
Why you see it that way: As we top the hill, you turn your head slightly leftward so that the deer remain directly in your binocular line of vision. But, as you turn your attention back to the driveway, to make your way down the backside of the hill, the deer fall into your peripheral vision, the area just outside the line of direct sight; they become a fuzzy clump of tan blobs off to your left.
Why you see it that way: Your “front-of-the-face” eye placement prompts you to turn around for a full view to better analyze the situation. His reaction: Because your horse must see an image with both sides of his brain before determining whether it’s friend or foe, viewing objects with one eye doesn’t adequately acclimate him to them.
What you see: My neighbor, standing ahead of us at the end of the driveway, wearing a Panama hat with a hot-pink hatband, a brown-and-yellow striped pullover shirt, and a pair of unsightly, bilious-green stretch pants. What your horse sees: A large human with green legs, a yellow and gray-toned body, and a brown/gray straw-looking thing on her head, which may or may not be edible.
Why he sees it that way: Your horse can perceive some colors: The most vivid to his eyes are yellow, followed by green, then blue. So long as my neighbor doesn’t make any sudden, startling movements, he’ll quietly accept her presence.
What you see: My fashion-impaired neighbor offering us a piece of pie while motioning to a small, grassy paddock where we can put our horses. Your reaction: You unpack your horse, turn him loose in the paddock, and chow down on a helping of fresh peach pie.
Why he sees it that way: Since he was designed to feed himself by grazing, he readily identifies food at ground level. While grazing, your horse remains aware of his surroundings to detect potential threats by looking through the tops of his bifocal eyes.
If he perceives anything warranting closer examination, he’ll raise his head and arch his neck, so he can continue to use the top halves of his eyes. He’ll then zoom in on the suspicious object with his binocular vision, phasing out any distracting peripheral scenes.
Your reaction: You hurry to finish your pie, re-tack your horse, and head back up the driveway, hoping to return to the barn before total darkness descends. Why he sees them that way: Due to the low-light perceiving receptors in his eyes, your horse’s night vision is about 50 percent better than yours.
The agile bay barely breaks stride as he sums up, locks on and leaves each ditch, drop or angled rail behind him. The complexity of modern cross-country and showjumping courses means that horses must tackle a huge variety of fences that flash up in quick succession.
The fact that so many cope with the visual challenge of our man-made designs to go clear is all the more remarkable given that we don’t really know what horses can see. Many experts are of the opinion that defining what horses see is a gray area, with lack of scientific knowledge enabling little more than a broad-brush account of how they might interact with their environment.
“While it may never be possible to view the world through the eyes of a horse, by comparing aspects of equine and human vision, we can explore similarities and differences,” says Dr Carol Hall, who outlines some key points: While we rely largely on binocular vision via frontally placed eyes, which allows good depth perception for judging distance, horses have large, laterally placed eyes, which can work individually to provide monocular vision, giving them a greater field of view for spotting predators.
Ears and eyes make the horse's head expressive to humans but also to other horses, new research shows. This seems obvious, but research was needed to see what happened when horses were deprived of eye and ear signals from their companions.
Researchers in Great Britain have documented a way to show that horses are sensitive to the facial expressions and the attention of other horses, including the direction of the eyes and ears. The findings, reported in the Cell Press journal Current Biology on August 4, 2014, are a reminder for us to look beyond our own limitations and recognize that other species may communicate in ways that we can’t, the researchers say.
The new study also challenges the earlier-held notion that animals with eyes to the sides of their heads cannot glean information based on the direction of one another’s gaze. Nathan and the study’s senior author Karen Macomb took photographs to document cues given by horses when they were paying attention to something.
In some instances, the researchers also manipulated the image to remove information from key facial areas, including the eyes and the ears. The ability to correctly judge attention also varied depending on the identity of the horse pictured, suggesting that individual facial features may be important, the researchers report.
“ Horses display some same complex and fluid social organization that we have as humans and that we also see in chimpanzees, elephants, and dolphins,” Nathan says. By David Saucer, DVD Horses have more than their fair share of eye problems when compared to other domestic animals.
Before reviewing some of the more common problems, here are some fun facts regarding equine eyes : • Horses have the largest globe of all land mammals. • The far lateral position of the eye on the outside of the skull, the rather bug-eyed conformation and the horizontal orientation of the pupil give the horse a wide monocular (two-dimensional) field of vision (each eye can see 195º from side to side and 175º from top to bottom).
Application of an ice pack reduces pain & swelling and, if the horse tolerates the initial shock of cold, they might like it. Generally treatment results in rapid improvement, unless there is more injury than simply a swollen eyelid.
For example, fracture of the bones of the orbit, hemorrhage into the anterior chamber, uveitis, dislocation of the lens, and retinal detachment. With an allergic reaction, generally both eyelids swell, as do other head structures, such as the muzzle and nostrils.
Allergic reactions that result in eye & head swelling can be quite serious and may require immediate veterinary attention. Sharp objects do a wonderful job of scratching, until one unfortunately hooks into the skin, causing the horse to jerk its head back and tear the edge of the eyelid, leaving it hanging below the eye from its remaining attachment.
When repairing such injuries, it is important to preserve the normal anatomical margin of the eyelid to ensure its proper function of cleaning the surface of the eye and keeping it moist. Obstruction of this duct results in an overflow of tears, which end up streaming down the face.
The skin below the eye gets irritated and attracts dirt and debris from the chronic wetness. In some cases, the blockage is permanent, such as the result of damage to the skull, tumors, or scar tissue within the duct.
Consequently, it is not so surprising that they commonly suffer injury to the eye, including abrasion to the cornea. Corneal scratches are extremely painful, unlike simple eyelid swelling.
The damaged cornea causes inflammation deeper into the eye, called uveitis. Treatment consists of topical ophthalmic antibiotics to help defend against bacterial infection.
Equine Recurrent Uveitis (Era) This disease is more commonly known as Moon Blindness. There is a more insidious form of Moon Blindness, which is more common in Appaloosa and draft breeds.