eyeball horse sight

Horse Sight – Impact on Fence Design and Materials

Horse sight is quite different to ours and this does impact on horse fence design.

Not many horse owners have a clear understanding of what horses actually see and fall into some common errors. A typical comment which I hear a lot is something like “I want a bright coloured rail so the horses can see the top of the fence”. Put quite simply horses sight does not depend on brightness and colour as much as ours, they often see darker more muted colours like blacks more clearly than bright colours including white.

Horses also have a tendency to be focused on objects in the distance. I refer to them as being “far sighted” but not in the sense your optometrist would use the phrase. The horse’s eye is designed to scan the horizon (note the pupil is a horizontal rectangle) and as such potential predators at distance are of particular interest and understandably elicit a heightened state of awareness. It appears that the horse’s overall approach to unidentified objects is to treat them as potentially harmful until proven otherwise.

As opposed to not being able to see things that are close to them, it would seem (sorry for the over simplification) they just tend to focus into the horizon. This is increasingly so when the horses’ flight instinct takes hold which makes them even more “far sighted”. Horses when startled will set their sight on the horizon looking for safety and lose consciousness of objects that are quite near to them. This has an impact on designing a safe horse paddock and obviously fencing and requires a little thinking and ingenuity.

So what can we do to make our horse fencing safe considering horse sight?

Use highly visible fence materials

Visible fences prevent playful horses running into them. Although may assert that “horses are blinded by fear” it is important to minimise risk within their normal behaviour as well. When considering fencing materials do not be fooled by the bright is best marketing of some horse fence suppliers.

Blog 8 - Horse sight colour wheels

We can make our horse fencing visible without turning it into the hi-vis factory look.

Keep it in mind, although there is still much research to do in this area, that horses have a different colour perception to us. Humans have three different types of retinal cells, and horse only two. They do indeed see colour, and not merely black and white, but have some limitations in colour differentiation.

Some have suggested that horses are red/green colour blind; others suggest they struggle to interpret blue and green which they see as a white/gray. It is therefore possible that horses would struggle to see white fencing against a back drop of green grass and or blue sky. There are many theories, some studies, and a lot of colloquial evidence regarding horse sight. However no credible sources have suggested that horses would have difficulty differentiating dark colours against lighter colours like blue, green or light grey in the background.

Therefore we suspect that strong black coloured horse fence posts and rails may be more visible to horses than white (particularly if dirty), browns or other bright or light colours. Certainly there is some suggestion that brown fencing (which contains the red pigment) may not be clearly differentiated from green (grass) in the background. The diagram to the right (and above) might give food for thought regarding colours and safety of horses, Diagram courtesy of [Carroll, J., Murphy, C. J., Neitz, M., Ver Hoeve, J. N., Neitz, J. (2001). Photo pigment basis for dichromatic colour vision in the horse. Journal of Vision, 1, 80-87.

Blog 8 - Horse Sight apples

These photos to the left indicate how human and horse sight differs.

The photos on top are how we humans would see a red and green apple.

The photos below are a digitized representation of how horses might see the same apples.

Notice how red and green are both “browned out”.  So much of their colour spectrum is slightly yellow, slightly brown, slightly green all lacking differentiation. This makes a mockery of the idea some owners have a hanging a red rag on a wire fence to make it more visible.

This image was taken from wikipedia equine vision.

Remember when considering horse sight colour is not everything

Look for broad panels and rails, and avoid thin wires and ropes. Particularly, makes sure posts and top rails are significantly broad and can’t be missed. Thin wires and ropes often disappear in the background and this can be very problematic if the posts blend in to back ground colours (e.g. old timber posters that have turned grey and pale with thin wires between can be difficult for even the owners to see).

In particular make sure the top rail is sufficiently broad to gain attention and promote visibility.

Make sure the horse fence is the appropriate height.

Horses tend to focus on the distance so try to get the top rail in their line of sight and don’t allow them to just look over and therefore beyond the fence. If the top rail crosses their line of sight you have created a safer environment, they can’t help but see the fence. Typically horse fencing is between 1350 and 1500mm high but this can vary with the size of the animals.
Consider the topography of the land, e.g. if fence lines are in a depression this can lead to horses simply looking over the fence and paying it no respect. In these cases it pays to be creative, consider the below section “Think big around boundaries”.

Think big around boundaries

If horses tend to see into the distance and beyond their boundary fencing it makes sense that they can navigate based on large objects around the perimeter. Put simply it is possible that your horses no they are near the fence line, not because they are focused on the fence itself but rather because they see the barn/stable/trees which they know are on the other side of the fence.
So when planning your paddock design try and build in some obvious landmarks that will you’re your horses navigate. It can be particularly important around known active areas. This can be as simple as planting some large shrubs or trees outside the fencing line which also can beautify your property.

For further ideas and thoughts on using living boundaries see Equos Blog – Living Fence lines.

Get them familiar with their yards

It is critical to make sure horses are familiar with their new enclosures. Be diligent and careful when moving horses into a new enclosure, make sure they get familiar with every boundary object and obstacle. Keep in mind they don’t simply look around of their own accord. There are far more benefits to this than merely fence safety but general horse well being and reducing stress to animals when moved. Remember the horses “prey instinct” leads them to believe an object is a threat till proven otherwise. Simply, do your best to prove everything they can see from their yard is not a threat.  Horse sight is different to yours, so an up-close look in good light conditions with owner in hand can give them more confidence in their new surroundings.

It may also be beneficial to give them a good walk around their new enclosure on the first night. Horses may have limited colour differentiating ability but they have superior night vision to us humans by far. This in part if proved by science, referencing their large pupil in a rectangular slit, a reflective tapetum which acts as an internal light reflector, and more rod photoreceptors.  They also have enhanced vision on cloudy days and in low light conditions, perhaps this reflects their nature of being most active around dawn and dusk. Simply put they will see threats at night that we would not even be aware of. So a good walk around on the first night with the owner, can teach them that some of the things they do see are not in fact threats but a natural part of the environment. Keep in mind what might go on at night around your property on particular occasions. It might be relevant to walk them around on the first night that activity is happening nearby (party next door or heavy traffic nearby) as part of their familiarisation.

It is often recommended to turn them out into yards early in the day when seeing is at its best. This will familiarise the horses to the environment early in the day and they can learn their landscape. Others suggest the middle of the day, as this is when they are most docile. Either way earlier in the day rather than later would seem to be advantageous.

Changes in light levels

A trade off for having enhanced night vision horses is that horses have a relatively slow response to changes in light. Situations where this might occur is when moving into or out from a dark barn or in and out of a float. It seems they have particular difficulty adjusting their vision when going from light to dark. Often horses will fright simply because they cannot see clearly any potential threats they might be about to experience. Again, horse owners can minimise these risks by walking them through the experience calmly and slowly, in particular when first introducing them to areas where the light changes.

Prepare for impact

Despite everything we do to minimise risk to horses of impact with fencing we simply have to prepare for the possibility that it might still occur. Consider the following basics of horse fence properties required to minimise the risk of injury when impact does occur;
1) The horse fence needs to be sturdy. Wobbly fences, unstrained wires and loose-fitting rails are far more dangerous than sturdy built and maintained fences. Sturdy fences tend to prevent entrapment and discourage repeated impacts.
2) The horse fence needs to have some give, but never fail. Some give but yet still sturdy.
3) The horse fence needs to be smooth (not abrasive or sharp like wire products)
4) The horse fence and all fittings need to be low profile. A significant proportion of horse injuries occur with impact to fittings so consider these carefully.
5) Consider upfront what maintenance is required to keep the fence safe.

Further Reading and acknowledgements

Carroll, J., Murphy, C. J., Neitz, M., Ver Hoeve, J. N., Neitz, J. (2001). Photopigment basis for dichromatic color vision in the horse. Journal of Vision, 1, 80-87.

For a useful summary on horse sight see:

The information provided is a suggestion only. This information is general only and it is up to the individual to ensure they use the correct fencing method suitable to their situation. Acacia Products will not assume responsibility for design choice by the installer. If unsure it is recommended that the owner of the property seek further advice through an approved Fencing Contractor. The views described in this article are of the individual and not the company. Always seek specific advice and consider you application carefully.

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