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 The Brain of the Horse..... and the Central Nervous System

This web site offers an overall picture of the equine central nervous system but cannot cover the entire subject. For more in depth information we have a list of resources that can get you started.  Resourses 

I have done my best to break down or simplify a subject that is vast. As they say "just the tip of the ice burg".

The Brain & the Central Nervous System

How do we have any idea what is going on in a horse's brain? Of course we can not ask a horse how they feel, or if they remember the task we asked of them the day before, but we can use technical tools to measure and use our observation through:

Science - is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions.

Natural science - a branch of science concerned with the description, prediction, and understanding of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatability of findings are used to try to ensure the validity of scientific advances.

Biological Markers - through chemicals tested in blood ,feces, and urine.

Biology is concerned with the characteristics, classification and behaviors of organisms, as well as how species were formed and their interactions with each other and the environment.

Understanding the similarities and differences of the mammalian brain offers clearer insight to the form and function of the brain and central nervous system of each species. 

Central Nervous System

The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord. The central nervous system is so named because it integrates information it receives from, and coordinates and influences the activity of, all parts of the body. CNS has three main functions: sensory, integrative (including mental function), and motor function.

Information comes in through the sensory receptors- in the ears, nose, mouth, eyes, skin and motor. These feed information to the CNS.

The Autonomic Nervous System -

The brain itself sits quietly in the dark waiting for input from the outside world. Stimulation from the outside world comes in via the eyes, ears, nose, taste, skin, muscles, nerves etc. From this information it layers on experiences that forms information about the way to respond to future events.

Wikipedia -The Autonomic Nervous System is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.

Do you want a successful outcome? 

Learn what really makes your horse tick....

Neuro transmitters are the messengers via neurons in the brain for chemicals like dopamine, adrenaline, serotonin, cortisol and other hormones that help all mammals navigate their worlds. The horse's reality is just an interpretation of the information their senses are experiencing. This interpretation is based on a long history of information from their past environment about how to survive in the world.

Horses are navigating in two worlds when we are with them. They live in a world of self preservation so they can survive and procreate, but they also have to deal with ours.

As we understand it, our world view is much more complicated than theirs.  Our world view consists of stories we have built from childhood that help us survive and thrive. Some of these human stories are beneficial and some are not.  Because of their very small frontal lobe, horses are incapable of coming up with their own stories about the past present or future and have no way to understand ours.

Neurons Neurotransmitter Synapse     

An electric energy party in motion all the time. 

We all have them. Neurons are found in the brain and gut. They are the nuts and bolts of brain and gut function. 

When I first learned about the Neurons, White and Gray matter and all the chemicals involved, I was astonished at the complexity of our bodies. Just like all other parts of the body it has a function. That function is to receive information, store it, and then reuse that information to come up with a story, a plan, identifications and many other grerufyggye.

All animals including humans have a view of the world based on the information that has been collected from their environment. From the womb to death our brains are capable of changes. Our brains have "plasticity"- they stay malleable and are able to learn and form new memories.

This is a good thing when working with and handling horses. 

Human Brain and Horse Brain

The human brain is larger than a horse's and has a larger frontal lobe. The frontal lobe is where stories are created and executive function happens.

Horses have very little frontal lobe so they lack the capability to form stories around an event or person. What the horse DOES have is a cerebellum that is 5 times larger than ours. When it comes to  physical motor skills and remembering where a river is, where good pasture is and where previous sightings of predators were, they are MUCH "smarter" than humans. Their brains developed this way because these issues are critical to their survival in their environment.

Autonomic Nervous System

Parasympathetic nervous system.

"Rest-and-Digest" or "Feed and Breed"

  • Urination
  • Digestion
  • Defecation
  • Calming of the nerves
  • Homeostasis
  • Enhanced digestion
  • Contraction of pupil for closer vision
  • Relaxed state stimulating sexual arousal

Neurochemicals that are asscociated with

"Rest-and-Digest" or "Feed and Breed"


The parasympathetic nervous system uses chiefly acetylcholine  as its neurotransmitter.

The brain contains a number of

acetylcholine areas, each with distinct functions; such as playing an important role in arousal, attention, memory and motivation


Sympathetic nervous system

"Fight or Flight"

  • Control of most of the body's internal organs
  • Accelerates heart rate
  • Widens bronchial passages
  • Decreases movement of the large intestines
  • Constricts blood vessels
  • Causes the eyes to dilate
  • Raises blood pressure

Neurochemicals that are associated with

"Fight or Flight"

One of the chemicals we are used to hearing about is Adrenaline plays an important role in the fight-or-flight response by increasing blood flow to muscles, output of the heart, pupil dilation response, and blood sugar level

Neurochemicals - Neurotransmitters

Neurotransmitters play a major role in shaping everyday life and functions. Their exact numbers are unknown, but more than 200 chemical messengers have been uniquely identified.


Dopamin- signals the horses motivational prominence (i.e., the desirability or aversiveness) of an outcome, which in turn propels the horses behavior toward or away from achieving that outcome. 

Dopamine is a rewarding substance in the brain which is useful when motivating a horse to learn something new.

Homeostasis- Its like a thermostat- regulating so we nd the horse feels just right...

Homeostasis is the state of steady internal conditions maintained by living things.

This dynamic state of equilibrium is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits (homeostatic range)

Not in Homeostasis

This horse is a bit high up in its sympathetic nervous system and is in a state of chaos. There is no learning or cooperation happening. 

In Homeostasis

Sharon Wilsie of "Horse Speak" refers to this as Zero, Which is easier to get a handle on when working with a horse. Focusing on understanding  HomeostasisZero will assist with all levels of working with your horse.

The outside world, through the sensory neurons, is constantly giving the horse's brain feedback for its next move. This contributes to the formation of their world view.

Sight- Photoreceptors
Horses have the largest eyes of any land mammal. 

The visual cortex of the brain is one of the most complex. The visual information is received and compared to the horse's internal model then new information is added. Then a response is formed. 

When Lucinda gives a talk she explains more in-depth on sight.

Smell- Olfactory Receptors

Horses get a huge amount of information from smelling poop.

  • What kind of animal?
  • Is that animal a threat? 
  • The health of another animal
  • The animal's emotional state
  • Is animal in estrus?
  • What direction the other animal was going?
  • The sex of another animal
  • How long ago was the animal there?

Scent Detection
Of narcotics/ people

Hearing- Auditory Receptors

A herd of horses has many, many ears all working together for the protection of the group and can hear over very long distances. The Cavalry in war counted on this for early detection of the enemy. 

The horse’s eyes don’t actually move much. The horizontal iris allows them to see both forward and backward at the same time. Prey animals generally have a much wider field of vision than predators. 

Here, the ear and the eye are seeking information in the same direction.

Touch- Exteroceptors

In-bonding: Oxytocin can increase positive attitudes toward individuals with similar characteristics.

Out-group: Oxytocin can also increase negative attitudes toward individuals who are dissimilar.

Touch: It has been found that it takes just seconds for oxytocin to be released into the bloodstream in both humans and animals.

By the way, she saved her horse

Mare and foal bonding

It is much easier to get along with a horse when we acknowledge their needs based on their sensory receptors

Stretch Receptors

  • Equal distribution of load on muscles
  • Position sense


  • Movement sense
  • Positioning

Whiskers / Vibrissae

  • There are no nerves in the hairs themselves, but each follicle has its own distinct nerve and blood supply.
  • These nerves are important sensory organs that detect vibrational energy, heat, density of an item. 
  • When you think a horse is smelling something there is a good chance they are investigating with these sensory tools.

Down Regulation

Keeping constant pressure on the rein or leg will lead to
"down regulating" of the sensory cells desensitizing the sensory receptors. 
This deadens, or habituates, the sensory information processing. 

"An example of down regulation is the cellular decrease in the number of receptors to a molecule, such as a hormone or neurotransmitter, which reduces the cell's sensitivity to the molecule".

Having a horse learn how to down regulate themselves from a potentially threating stimulus is important for the safty of both humand and horse.  

Trigeminal Nerve

Controls Facial Muscles

  • Emotions and Pain
  • Stressed



Tom Dorrance understood the central nervous system and learning in his own way....

People, like horses, need practiced repetition so their reflexes are working for the task easily.

Today's quote from Tom:
"Well, you still have to learn how, just as the horse has to learn. If you start to do something with your left hand that you haven't been used to doing, even though you know what you want to do, you still have to get your reflexes so they will respond to what you are thinking."

Tom was a observational genius. He could read the whole horse. Now with our current level of information from ethology, neuroscience and biology we can understand "the HOW" of Tom's teachings and WHY his teaching is/was so effective with the horse.

What he is referring to in neuroscience is the chemistry and growth of myelination of the neuron (this had to be done over time with repetition). He also knew that is was imperative for a horse to be operating in or close to Homeostasis.

Thank you Mr. Dorrance 

The Central Nervous System 

Sight, Sound, Smell, Taste, Touch, and  synchronization of all our sense and the horses senses are then woven together to help us navigate the world around us. All animal species are highly intelligent in their own environment- otherwise they would not have survived.