There are many myths in the horse world, that have many horse owners either scratching their heads wondering is this really true, or blindly following the faux advice as gospel. The myths surrounding magnesium is a big one that really needs to be ironed out.
I should start with the first most important point that, horses do in fact need magnesium in their diet because naturally very often the feed that they graze on is just not sufficient to keep their needs met. But that is not the part of things that is the MYTH.
Where people are led a stray is that anxious horses should be given as a calming product, and that the standard Magnesium Oxide powder “didn’t work for my horse”. The misconception is that when you give your horse mag in one form or another, that you should see a visible result and that is usually expected to be “calming”. The problem is though that if you DO get the calming effect from magnesium or a supplement containing magnesium in one of it’s forms, you are likely actually overdosing and doing harm.
The body needs magnesium and many other minerals to perform at it’s peak, but there should not be huge obvious visible changes in the outward appearance of the horse unless they have been really poorly lacking and then you might see a slight recovery, but normally not so much.
So when people have a highly strung, anxious, hot, jiggy horse (along with all the other descriptions people give to describe a horse that needs to calm down) they are often told to reach for the mag, and unsurprisingly they are left to feel like it “didn’t work” but it was never going to because of what mag actually does.
So the next time you want something to actually calm your horse, instead of inadvertently overdosing them with too much of a mineral, look into what it is that said mineral ACTUALLY does in the horses system, and you will likely find that you are left to look for an alternative option. There are a tonne of them too (alternative options that is) that range from herbs all the way through to handling and training, though you may well find that there is no quick fix, but you will at least not be giving something that is doing more harm than good at worst, at best being a waste of time and money.

There are many great websites that discuss the needs of horses when it comes to mineral suppliments with all the info that you need to work out dosage and daily needs, so before you reach for a supliment to solve a behavioural problem, think of THE MAG MYTH and take a closer look before listening to the say so of others. Your horse will thank you for it!