As the physiology of the brain suggests, horses are sensory animals. So let us first explore the main senses of the horse.

VISION

Vision is one of the horse’s most significant senses when considering survival. Their eyes are positioned on the sides of the head, giving mostly monocular vision, but affording the animal approximately a 350º view of what surrounds them. Small blindspots occur under the horse’s head, between the eyes and around the forehead, with another, larger blindspot occurring directly behind his tail.

Binocular vision is possible from a short distance in front of the horse’s face and is required for depth perception, allowing the horse to judge the ground conditions in front of him with more accuracy.

When viewing something in the distance, the horse will raise his head in order to look through the lower part of the lens, and when viewing something close up or low down (such as a jump, for example) he will lower his head to look through the upper part of the lens.

THE EYE

The equine eye has excellent night vision, but reduced visibility in very bright conditions. We are unsure exactly which colours of the spectrum the horse can see but we do know that they perceive fewer colours than the human eye does. Research into this area is continual but it seems that no definitive answer is forthcoming as yet (at the time of writing).

HEARING

The horse’s ears have the ability to rotate through 180º and can move independently of one another, thereby allowing the horse to analyse sound from more than one direction at a time, or to confirm the direction in which he believes a particular sound is coming from.

The equine ear detects sound at a higher frequency than the human ear. This means that they can hear sounds of a higher pitch than we can but we can hear sounds of a lower pitch than the horse can. This does not necessarily mean that the horse does not have an awareness of lower pitched sounds, he may just detect them in a different way, i.e. through vibration. Such large external ears are key to better and clearer hearing as the larger the pinna (external ear) the more efficiently they collect the sound waves and direct them to the inner ear. For example, if you cup one hand around behind your own ear, you will discover that sounds become much clearer and more amplified.

It may be noted that horses have a tendency to appear more nervous on a windy day. The rustling of the leaves on trees and bushes can be overwhelming to the horse’s auditory senses, causing this crucial survival mechanism to become ineffective or, at best, severely impaired by the meaningless sound. This in turn causes the horse to become more vigilant in the use of his other senses and, therefore, he may become more spooky towards his environment as he will have a tendency to be ready with a flight reaction much sooner than would normally be the case.

SMELL

The horse appears to have a much more highly developed sense of smell than a human. The olfactory bulbs at the front of the horse’s brain are significantly larger, and the nasal passage (which contains many layers of scent-sensitive cells known as the Jacobson’s organ) is far longer.

Horses use smell as a primary means of recognition and analyses. It is, therefore, very important that we give them time to become familiar with an unknown smell, perhaps of an object or new location. On occasion horses will produce very loud, forced exhalations through the nasal passage. This is done to clear the nasal cavity in order to take a sample of the air for clearer analyses. This resounding ‘snort’ may be read as uncertainty or fear and may also serve as a warning, to other horses in the vicinity, of a potential threat.

Horses also produce a Flehmen response when they wish to analyse a particular scent further. This response is stimulated by certain odours, such as pheromones (behaviour-altering chemicals produced by other animals). They draw in a sample of the air and then lift the upper lip up to close off the nostrils, thereby trapping the scent inside the Jacobson’s organ for further scrutiny.

TOUCH/FEEL

The whiskers that grow around the horse’s muzzle and eyes are incredibly important. Every single one has its own specific nerve and blood supply. They are used by the horse to help protect vital areas such as the eyes, mouth and nose. The whiskers help to prevent him from knocking into things and causing injury, by detecting things which may be in a blind spot or that are too close for the vision to focus upon.

The horse also uses the whiskers for investigation. They will get close to an object and brush it with their whiskers to ‘feel’ it before moving on to investigate further with their lips. It can often look as though the horse is smelling the object when in fact that was already done from some distance away. The horse explores in this way, as we would explore something with our fingertips before picking it up to analyse it further.

So when a horse wishes to investigate something, they process it with their vision first, then smell, then they touch it with their whiskers. Sometimes this is sufficient information but often the object will be subjected to further scrutiny by the lips, then the teeth, and finally the inside of the mouth.