Today I want to discuss something that I recently had to learn about for the sake of my own horse - Magnesium.
Magnesium itself serves many purposes in the body, but primarily it acts as a neurotransmitter. That's a very big and scary word to say that it boops the next neuron in a chain to tell it to continue firing on down the line of neurons and eventually produce a result, like their head turning. Magnesium also helps to relax muscles by binding to them in place of Calcium, which would cause the muscles to contract.
So what does this have to do with supplements? Well, I'll use Sid's case as an example. I like to get his hay tested wherever he is living so I have a handle on exactly what his intake is. While in Pennsylvania, I noted that his hay was relatively high in Magnesium. Upon asking my vet about this, she said that our soil was high in Magnesium, and that leeches into the grasses and hay grown there. When Sid and I moved to Colorado, within a few days I began to notice a change in his behavior. He was spooky, twitchy, and irritable, despite continuing on turnout and no feed change. Then his hay test results returned, and low-and-behold the Magnesium levels were MUCH lower than they had been in PA. So I began to research how this could impact my horse.
Because Magnesium plays such an important role in the nervous system, a deficiency, or even a sudden drop the body can't anticipate, can cause many things. Primarily, it results in a more anxious horse. The body recognizes that it may have slower response times as a result of the lower levels of neurotransmitter, and so creates an overreaction to everything in an effort to compensate. This also means that the brain doesn't process things as well, so something your horse may have worked through being afraid of in the previous ride may suddenly be terrifying again, until they re-familiarize themselves with it.
In the case of Sid, this increased stress and muscle activity also resulted in a mild case of ulcers. However, once I began supplementing with Magnesium (specifically HorseTech, Inc.'s MMX formula), I saw a change in his behavior. He returned to the horse I had on the east coast - quiet, easygoing, and much happier.