Excess Energy, 'Lack of Discipline' (ugh!) or ‘Grass-Affected’?
- Jenny Paterson

- 3 days ago
- 3 min read
Not understanding the difference leads to ‘misdiagnosis’ and ‘mistreatment’ of the horse (meaning inappropriate treatment).
There is a BIG difference between a horse whose nervous system is disturbed by the mineral/nutrient imbalances in Spring (or Autumn) grass and one that merely has excess energy from 'sugars'.
Excess ‘sugars’ will generate excess energy for the horse while his brain, nerves and muscles are still functioning perfectly. He ‘rounds up’ and becomes like a coiled spring, he still has control of his mind and his body. He knows what he is doing.

In this state, the horse feels energetic (fresh) but not out of control or scary.
By contrast the seriously ‘grass-affected’ horse has no idea what he is doing. All his senses are on high alert so he ‘reacts’ instead of ‘responds’.
In this state he cannot ‘learn’, there is no ‘reasoning’ with him and discipline is completely inappropriate because he can’t help it.
‘Disciplining’ horses went ‘out with the ark’ years ago – the vast majority of horse owners now are much more sophisticated with their horsemanship and totally understand why punishing a horse is not the way.
There is a spectrum of 'spookiness' - most horses will 'look' at unfamiliar objects. What is not normal is for them to be constantly on edge or violently spook at minor distractions or noises..
A big tell-tale sign the horse is ‘grass-affected’ are the tight muscles that go along with hollow posture. The horse is prone to getting faster and faster and when he does buck it is more violent and unpredictable than a bucking horse in a rodeo because it is ‘frantic’. VERY SCARY & DANGEROUS...

It is easy to think that horses become ‘grass-affected’ due to ‘energy imbalance’ (Too much feed, not enough work). However, a horse who has excess energy is comparatively EASY to handle compared to a ‘grass-affected’ horse who is ‘nuts’, ‘crazy’, ‘fire-breathing dragon’ because his brain, nerves and muscles are malfunctioning.
You only need to compare their posture. The horse with excess energy tends to ‘round up’, engage and bounce. You can allow him to let off the excess steam in the round-pen or on the lunge. The horse will zoom around, throwing in a few bucks but soon run off the excess energy and be ready to ride.
Look at a picture of a truly ‘grass-affected’ horse and you will observe it looks the opposite –the head is up with nose to the sky, eye-balls on stalks and tail up – ie they travel ‘hollow’ and simply CANNOT round up. He has no self-awareness and is liable to hurt himself and you. They will easily get into a lather and go until they drop. This is impossible and/or dangerous to lunge - let alone ride.
In these cases it’s simple – don’t get on!
A seriously ‘grass-affected’ horse is liable to explode as the rider is in the process of mounting (an extremely dangerous moment) or sometimes after a step or two.
Yet there are still people/instructors telling owners to 'just get on and ride' these horses!
We could write a book full to the brim of the consequences – serious, some of them life-changing, accidents that result from not heeding the warning signs.
The pictures demonstrate the difference between the two.
One is frantic, explosive and the horse is NOT HAPPY while in the other they are playful and VERY HAPPY!




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