Horse senses

A horse’s senses include smell (olfactory), taste (gustatory), sight (vision), hearing (auditory), and touch (tactile). Horses are prey animals, which means they must always be aware of their environment in case of predators.

The effectiveness of your horse’s senses makes them sensitive to the world around them, which is likely the reason they shy away from plastic bags and spook at birds flying from hedges!

Smell

Your horse uses their sense of smell to investigate new objects (like that new feed bucket or jump wing) and to make new friends, though they can also identify old friends by their scent. Horses may sniff a potential partner, to check whether they’re compatible, too.

Have you ever noticed your horse blow air (or snort!) at an unfamiliar object, prior to taking in a long, deep breath? Before they can take in new smells and learn about them, your horse needs to clear their nose of lingering odours. If there are smells already stuck in your horse’s nasal cavity, it could confuse their understanding of a curious, new scent!

As your horse has a nostril on either side of their muzzle, they’re able to smell two scents at once. If your horse has ever sniffed something strange, then suddenly curled their top lip and lifted their head into the air, that reaction is called the ‘Flehmen response’. By curling their top lip, your horse is trapping the new smell in their nose and sending it straight to their brain to process it promptly. 

Taste

The way your horse’s sense of taste works is just like yours; chemical messages from their tongue are sent to the brain to be processed. However, your horse uses their sense of taste slightly differently… 

Research suggests that horses use taste to test the nutrients in their food, as well as to check its quality and tastiness. For example, if your horse instinctively knows they’re lacking salt, they’ll seek a salt lick!

New tastes follow the same sensory pathway as your horse’s sense of smell. So, horses can instantly get important information about any new tastes and store it for the future (like filing away the memory of, say, poisonous plants or wormer, and avoiding those tastes – as best they can – from that moment on!).

Sight

Why do horses have eyes either side of their head?

Eyes are essential for a wild horse’s survival. Therefore, having eyes on either side of their head helps a horse to see long distance and have amazing peripheral (all-around) vision, allowing them to instantly scan their surroundings for predators.

Monocular vision

‘Monocular’ means ‘one eye’ and when horses use monocular vision, they’re using each eye separately to survey the surrounding landscape. For example, your horse will tend to use monocular vision when looking across an open field. 

‘Blinkers’ are an attachment to a bridle that prevent a horse from using monocular vision. It is believed that blinkers help a horse to focus on what’s directly in front of them, instead of spooking at things around them (which could prove dangerous in some situations, such as carriage driving). 

Binocular vision

‘Binocular’ refers to the way your horse uses both eyes to view the path directly in front of them. Horses use binocular vision when navigating uneven bridlepaths, for example, though they can also raise their head to use binocular vision to focus on distant objects, such as show jumps.

Blind spot

Although their eyesight is amazing, horses do have ‘blind spots’, which are spaces surrounding them that horses can’t see. Your horse has two blind spots.

Their first blind spot is a small space in front of them, meaning your horse cannot see directly in front of their face or right under their nose. For this reason, it’s important you approach horses from their shoulder, since they’re easily startled when people approach facing their forehead. 

Having a blind spot in front of their face also requires your horse to work harder when approaching obstacles, which is why it’s important you allow them plenty of time to see where they’re going and steer them in straight lines when riding towards jumps!

A second blind spot is the space behind your horse’s tail. Approaching a horse from behind will likely startle them, so it’s essential you move to somewhere they can see you (like their shoulder), allowing them to react safely to your arrival.

Stereopsis

‘Stereopsis’ is a term used to describe depth perception. It was once thought that animals with eyes on either side of their head were unable to accurately judge distance and depth; though if you’ve ever ridden your horse over a jump or tried to encourage them to step into a puddle, you’ll know this isn’t true!

In fact, horses are said to have better depth perception than cats and there’s research to suggest horses share some depth perception skills with humans. 

Anatomy of your horse’s eye

Cornea

The cornea is the transparent outer layer of your horse’s eye and is the first part of their eye that light passes through.

Iris

Although beautifully colourful, the iris has an important job! The iris is responsible for controlling the amount of light that enters your horse’s pupil.

Pupil

That black rectangle in the centre of your horse’s eye is their pupil, which will contract (get smaller) in bright light and dilate (get bigger) in low light.

Lens

Sitting behind the iris and pupil, your horse’s lens focuses light onto the retina.

Retina

The retina contains millions of light-sensitive cells, known as ‘rods’ and ‘cones’, which collect visual information. After this, your horse’s optic nerve, deep within their eye, will send that visual information to their brain to be processed and understood.

Colour vision

Ignore the rumours that horses can’t see in colour!

It’s believed horses have ‘dichromatic vision’, meaning they can see two colours best – usually shades of yellow and blue. However, recent research by the University of Exeter, which helped improve safety in jump racing, suggests horses are unable to differentiate between shades of red and orange. 

Hearing

Your horse’s hearing has three main functions, which are to:

• Detect sounds.
• Determine the location of sound.
• Send sensory data to their brain, so they can identify sounds. 

Ears

Also known as a ‘pinnae’, your horse’s ears have some superhero-style skills:

• They can move independently, as well as in unison.
• Each ear has 16 muscles.
• Able to respond to sounds up to a whopping 4,400m away!
• Can rotate each pinna (ear) in an arc of 180 degrees (semi-circle).

Sound waves are formed by vibrations. If your horse is in range of sound waves (before those vibrations run out of energy and stop), they’ll hear that sound. The structure of your horse’s ear helps them capture more sound…

External ear

Cartilage (same as you have in your ear!) forms the funnel shape of your horse’s external ear. This funnel shape allows your horse’s ear to swiftly send sound waves straight to their ear drum.

Middle ear

Your horse’s middle ear is a chamber filled with air that sits behind their ear drum. Also located in your horse’s middle ear are the small bones that amplify vibrations and send them to the inner ear.

The pressure outside of your horse’s ear should be the same as the pressure within their middle ear, for them to hear sounds properly.

Inner ear

Ever heard of the ‘vestibular apparatus’? It plays a role in your horse’s balance. 

Inner ear cells – surrounding the vestibular apparatus – are responsible for converting sound waves into electrical impulses, which are then sent to your horse’s brain to be processed. 

Interpreting sound

Some sounds aren’t interpreted as noise by your horse. In fact, there are low frequency sounds that your horse picks up through their muzzle and hooves!

Touch

Perhaps their most powerful sense, touch has a huge impact on your horse’s life.

‘Receptor cells’ are responsible for your horse’s sense of touch, and these cells are located within your horse’s skin.

Your horse has ‘vibrissae’ (whiskers) around their muzzle and eyes that allow them to interpret their environment as well. These sensory hairs are essential for your horse to be able to understand their surroundings, so whiskers should never be trimmed for cosmetic purposes. Interestingly, Germany and Belgium have banned whisker removal!

Studies show that while mutually grooming another horse, your horse’s heart rate lowers – which helps them feel calm. Grooming is a behaviour that enables horses to form strong bonds with each other, too.

If you’re interested in learning more about your horse’s senses, speak to your local equine vet.