This post is for people who struggle with more extreme issues and who also struggle to understand what their horse's forage has to do with it.
It provides an explanation for these frequently asked questions:
Why do extreme reactions often come 'out of the blue'?
Why can horses be perfectly fine at home yet lose the plot when they get in a group or go somewhere different (maybe a show or event)?
Why their horse does a violent spook at normally insignificant things - such as birds flying out of a bush or even shadows on the ground?
Why can’t they handle their ‘friend’ going a mere 5 metres away?
Why has their horse suddenly developed 'allergies'?
Why do ulcers develop in so many pasture fed horses?
‘Normal’ nerve and muscle function requires internal equilibrium which the horse should be able to maintain via self-regulating mechanisms (homeostasis).
Chronic excess potassium intake from green, growing grass, clovers & lucerne disturbs internal equilibrium and causes an increase in ‘neuromuscular excitability’.
This instantly translates to ‘over-reactions’ to normal stimuli:
 *Not wanting to be touched or brushed
*Becoming dangerous to handle/ride
*Being violently spooky
*Explosive transitions especially trot-canter
*Random bolting
*Head-Shaking
The excitatory action of the potassium on nerves and muscles is boosted by various ‘sensitisers’ including:
Adrenalin - increased adrenalin secretion resulting from a strong emotion will trigger over excitability in horses. Any emotion or fear, eg a loud noise or a prick with a needle, will elicit a sudden secretion of adrenalin which instantly multiplies the effect.
Histamine - found to be present in larger quantities in the blood of animals consuming very young grass precipitates the release of adrenaline.
Grass LOVES potassium and luxury uptakes this mineral far more than its requirements. Fortunately potassium levels drop as the grass matures.
The over-arching solution therefore is to LOWER potassium intake by
Allowing grass to be grazed at a much later stage of growth or fed as hay
Feed as much hay as possible
Not adding high potassium items to feeds – lucerne/alfalfa, clover hay, molasses, kelp
Make sure horses are well mineralised with the other important minerals (salt, and a suitably formulated vitamin & mineral supplement)
Leave riding over-reactive horses until they are back to normal; it is far too risky.
