Equine eyesight questions answered, plus vets share advice on common vision problems to look out for

Horses have one of the largest eyes of any mammal, but how good is horse eyesight compared to ours? And what common problems should horse owners be ‘keeping an eye out’ for?

We’ve got all the information you need on equine vision and eyes right here – plus some advice from expert vets on how to spot an equine eye problem.

Do horses have good eyesight?

Horses are prey animals and have almost 360° vision – their only blind spots being beneath their chin and directly behind them – so that they can watch out for predators approaching from all directions at the same time as grazing.

They have good motion detection, which allows them to spot predators easily, and have better night vision than humans. Their ability to judge distance and depth is limited, especially as most of their field of view is monocular vision (with one eye), which is why they often raise their heads on approach to a fence. It also takes them longer to adjust from light to dark.

They have developed big, beautiful eyes that protrude from each side of their head. However, this also makes them more exposed, and therefore more vulnerable to blunt or sharp traumatic injury.

Can horses see in colour?

Imogen Johns FRCVS explained to H&H that it is “next to impossible to say for sure how ‘well’ a horse can see”, but we know that horses are dichromats, which makes them red-green colour blind. They can see blues and yellows but browns, oranges and shades of red and green are easily confused. Whereas humans, for example, are trichromats and can see the four basic colours of red, green, blue and yellow.

Horses are able to see very well in low light conditions, but need time to adapt from light to dark situations and vice versa, which is why jumping into and out of shaded areas is such a challenge when riding cross-country.

Signs of sight loss in horses

Karen Coumbe MRCVS told H&H what to look out for to keep your horse’s vision safe. Any sign of ocular pain in horses is always deemed an emergency and a prompt visit from your vet should be arranged if there is:

• An eyelid wound
• A closed or partially closed eye
• Discharge or pus coming from the eye
• A swollen eye or eyelid
• A reddened appearance
• An eyeball that suddenly turns cloudy or develops a discoloured area
• A painful eye, especially if there is also increased sensitivity to light

“A problem affecting one eye only can be an indication of something more serious,” says Karen Coumbe. “Always look out for other more subtle signs, such as downward-pointing eyelashes indicating a partially closed eyelid, or other subtle signs of eye trauma, such as discolouration.”

Causes of sight loss in horses

Ocular injuries generally result from impact, a penetration or an abrasion/laceration and among the most common injuries are abrasions of the globe (which can lead to the formation of a corneal ulcer) and periorbital lacerations (traumatic injuries sustained around the eye).

“To prevent problems, it is important to check your horse’s environment, minimising anything that could potentially injure them, such as thorny vegetation, protruding nails and rough edges around stabling,” says Karen. “Horses often rub their heads on any solid object available, especially during fly season. Interactions with other horses may increase the risk of eye injuries.”

Fly masks can be worn to prevent irritation and reduce the risk of injury – and they can provide UV protection, too.

Common horse eyesight problems

Other common horse eye problems that can potentially affect their vision include uveitis (also known as moon blindness) and immune-mediated keratitis. Uveitis means inflammation within the eye and is the most common cause of blindness in horses worldwide and a common cause of chronic eye pain.

Some horse eyesight problems are more common in older horses, including glaucoma or cataracts, or can be more serious, such as corneal disease.

The aim of veterinary treatment is always to save the eye. However, if this cannot be done or if the horse is going to be left with a chronically painful eye, then enucleation (removal of the globe) is a relatively uncomplicated surgery that can be performed. Horses and ponies tolerate the loss of an eye extremely well and appear to adapt easily – many are still able to be ridden, including jumping, after such a procedure.

Can horses cope with loss of vision?

Loss of vision in one eye is generally very well tolerated by horses – most horses are able to return to their “pre-enucleation” job

Loss of vision in both eyes is rare – while some blind horses do adapt, the personality of the horse, the facilities, environment, and input of the owner will all determine how successful the outcome is.

Can blind horses be trained?

Absolutely, training partially sighted horses and blind horses just requires a slightly more considered approach and there are many famous one-eyed horses who have gone on to have incredibly successful careers.

“Endo the Blind”, a US-based appaloosa gelding owned by Morgan Wagner, became famous for his spirit, showing that “blind horses are capable of anything” by claiming three world records aged 22.

At the age of eight he’d been diagnosed with glaucoma, cataracts and equine uveitis, but his record-breaking achievements included the highest free jump by a blind horse (106cm), the fastest time for a blind horse to weave five poles (9.93sec) and the most flying changes in a minute (39).

“Don’t have big goals, just what your horse can do, reward, and try a little bit more next time,” said Morgan.

An Italian racehorse named Laghat won 26 races despite being totally blind in his right eye and 95% blind in his left eye as a result of a fungal infection called mycosis.

“Laghat has a sixth sense, which tells him where to put his legs,” said owner Federico de Paola, who also rode the horse in amateur races.

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