The Equine Senses

Sight

 

    The eyes of a horse are beautiful, and also have a great function. As the eyes are located on the sides of a horse's head, the horse has a vision range of about 345 - 355 degrees. When grazing and moving their head back and forth, the horse practically has a 360 degree vision. This is probably the main reason that sight is an equine's most reliable sense.

    It takes longer for a horse's eye to adjust to darkness than our eyes, being as horses have pupils about six times the size of ours. Also contrasting, horses only have two types of cones sensitive to color, whereas humans have three. The hues and tones an equine can see are currently undetermined, although it has been verified that horses can see more than simply shades of gray.

Hearing

 

    The ear, which is similarly constructed to that of other mammals, is the most mobile ear of any domesticated animal. Horses can hear higher pitched sounds than we can, and tones almost as low. They do not hear the lowest sounds through their ears, but instead feel them through their hooves.

    Depending on the speed and direction of a wind, horses can hear noises that are a few miles away. Wind can help noises to reach a horse's ear, although it can also cause nervousness in a horse because of the sounds they can and cannot hear.

    Decibels (dB) are a logarithmic unit used for measuring the volume of sound, and it represents the energy of the sound. Every ten numbers is ten times the previous number - for example, 30 dB has a hundred times the energy of 10 dB, and 20 dB has a ten times the energy of 10 dB. Peaceful barn noises are about 20 to 35 dB, and sounds at or greater than 85 dB may harm hearing.

Volume of Common Sounds
Sound ---  Volume in dB (estimate)
Human breathing = 10
Rustle of leaves = 20
Whispering = 20 - 30
Mosquito flying = 40
Normal talking = 40 - 60
Bird tweeting = 60
Busy traffic = 65 - 80
Train nearby = 65 – 90
Vacuum nearby = 70 – 80
Telephone dial tone = 80
With repeated exposure, hearing damage begins = 85
OSHA regulations begin = 90
Heavy traffic = 90 
Lawnmower, firecrackers = 100
Tractor at 80% throttle = 100
Thunder = 100 - 130
Motorcycle, chainsaw = 110
OSHA requires protection = 115
Tickling sensation = 120
Rock concert, snowmobile = 120
Unsafe; pain occurs = 130
Jackhammer or gun = 130
Dynamite blast = 140
Physical damage occurs = 150
Jet nearby = 150
Rupture of eardrum = 160
Shotgun blast, muzzle end =160
Death = 200

Smell

 

    Using their great sense of smell, equine can detect most poisonous plants, as well as contaminated water.
    Linked in similarity, the sense of smell and taste are very profitable to horses. Odor corpuscles in the air deposit themselves on the horse’s nostrils, which have a fairly large surface area. The damp nostrils then process the information, and send it on to the brain. When meeting a new horse, the normal tradition is to smell the horse in question, without being smelled.

    The flehmen response is part of smelling, and this is when the horse curls his upper lip back. Doing this secures the scent into an area where the Jacobsons organ can process it further. This can often be triggered by identifying hormones in body fluids. Some horses will do this very commonly, but other horses have never been known to do it.

Taste

 

    The taste is processed by the papillae on the throat, palate, and tongue. When the horse is eating and drinking, the taste either accepts or rejects the food. If the food is rejected, the horse usually tries to spit it out; or if the horse was suspicious of the item beforehand, the horse will not eat it.
    Equine are born with a favor for salty tastes, and can quickly learn to savor sweet food. However, they tend to refrain from bitter and sour tastes. This is the reason why we sometimes conceal medication in something sweet, such as making wormers that are flavored like apples or carrots.

Touch

 

    Even though horses may be much larger than humans, that does not make them insensitive. In fact, horses are quite responsive to touch. Of course, depending on the training and type (cold-blooded, hot-blooded, or warmblood), some are more sensitive than others.
    For example, cold-blooded or draft-type horses generally have thicker skin, which makes them less sensitive, whereas a light horse (such as an Arab) will have thinner skin. However, one can work with any type of horse as a foal, and desensitize him to being touched on anywhere. They still will feel the touch in the same volume, but they won’t react as much to it.