Horse Vision and The Effects on Behaviour
It’s been said that the eyes are the window to the soul. Which is easy to relate to when spending time with horses, as their eyes give us a plethora of information.
As horses’ eyes not only express their mood and frame of mind but they are a major part of the equines innate and subtle body language too. Which can help us humans to “read” where the horse is at with both their behaviour and improve more refined communication between our two species.
Therefore, the more you can find out about how your horse sees the world the better understanding ca be acheived. . As I’ve found insight into how the horse's eyes work to be a critical aspect of understanding horses in a deeper level of equine behaviour, which for me has been particularly evident when working with special needs horses through the rehabilitation work that I’m involved with. Who are often shut down and trying to hide their emotions through enduring trauma, as whilst the body doesn’t always relay how the horse is feeling, the eyes always show the pain and worry, as well as when the horse is ready to engage, and even when they are asking humans for help because a horses eyes never lie.
This can play an enormous part in knowing the when’s, whys and how’s with horses, as well as understanding the reasoning for their actions, all of which can help improve our horsemanship skills and on how to better relate to the horses in our care.
This knowledge enables us to respond appropriately and certainly plays a huge and critical part of every horses’ successful rehabilitation through our work helping them back into trusting people again.
Here are a few facts about equine vision to help you understand how your horse sees you and their environment and how it can help you to better understand their behaviour.
Firstly, horses have one of the largest eye sizes compared to body size, of all land mammals, which tells us a lot about how important vision is to our equine friends. When a species has been hunted for 55 million years, it makes a lot of sense that horses have developed a large and incredibly efficient eye, as to help them spot all those potential predators, in order to give the horse the best chance of early detection of threat that has actively shaped their core behaviour and social interactions too.
The eyes are also a key part of the core central nervous system in the horse, and due to that are the first to be affected not only by the horse's environment but also by their diet, which can hinder or improve their macular health, depending on how suitable it is.
This means that the eyes are the first part of the body to be affected by grass sugars as well as grass toxicity through Mycotoxins, which is a critical reason on why you should never ride a toxic horse, in addition to why feeding a low sugar diet is paramount to equine health.Please see our link for ways to address this: https://www.naturalhorsenz.co.nz/recommended-feeding-plan
Another fact to consider is that whilst horses see in varying shades of greys and whites, they only see the colours of blue and green in their colour spectrum and the blue or green hues in between that.
Therefore, reds and oranges are not part of their colour vision and this can play an enormous part in their awareness. For example when using tack- there is not much point in waving an orange stick at a horse as the orange won’t be seen- it is better to use a blue or green if you want to get anything to particularly stand out to your horses vision or to use opposing colours next to each other such as white and black to show visual differences, such as when approaching jumps or other obstacles etc...
This limited colour outlook is due to the horse’s eyes only having two cones in their colour vision instead of three like humans. Which is shown how they see colours in the photos.
Another point to note is that horses have a field of vision of 350° out of a possible 360°. This occurs through 2 different types of vision using a mixture of binocular (two eyes) and monocular
(1 eye) sight.
The field of vision diagram shows these differences with horses having around 65°of their vision as using two eyes (binocular) and 285° being used as single eyes sight (monocular) with the blind spots immediately in front and directly to the rear.
This relates that your horse cannot see things that are up close to them with both eyes at once, so this would affect horses for example when they are worried about something ahead, and if they are allowed to back up from it, so they can look at it head-on from a distance, they will be able to see the object in more clarity and detail, with both eyes using their binocular sight.
As although the monocular sight shows a wide range of vision nearly all around the horse, through using both eyes independently, the drawbacks are poor visual accuracy, meaning that it’s not as clear and lacks depth, which is why horses jump sideways and spook at different things in their periphery, as these objects are not in the clear vision of that when using both eyes.
Therefore if you allow your horse to back up so he can see the object with improved accuracy when he’s worried about something, it’s normally at this point it helps the horse settle once the binocular vision picks up the finer details and relays that it’s not a lion in the bushes but only a plastic bag or coke can etc...
Now to address how well horses see in the dark:
Horses have more cones to rods ratios in their eyes than humans do, which means they do see better in the dark, however, this doesn’t mean all is better with their darker vision than humans.
For example, they don’t adapt as fast as us from changes in light, such as going from a light place to a dark place, like when being taken into a float or a shaded barn. As it takes a lot longer for their eyes to adapt to dark from light hence why some horses can be resistant to going in the float due to these visual limitations.
Therefore it’s best to try to load your horse into the float in a sheltered spot rather than in bright sunshine, which reduces the changes in the light and can help them to see the float to be less shadowy, helping to reduce resistance of loading for some horses.
Alternatively give your horse time to adjust to the changes in light when taking them into a darker space such as a float, or better still have a light and bright float inside to encourage them visually into the area.