Magnesium as a calming agent

Magnesium is one of the most common ingredients in calming supplements for horses.

It’s used for two reasons. First, magnesium supports muscle relaxation. Second, magnesium is involved in nervous system function and can help reduce hypersensitivity.

The question is, does magnesium work?

Horses that are deficient in magnesium may have muscles spasms, tight muscles or exhibit anxiety and in cases where supplementation helps balance your horse’s diet, you can see a marked improvement. However, if your horse is not deficient in magnesium, it probably won’t help at all. In general, I believe that as horse owners we spend too much time and money trying to find the “magic pill” that will turn our horses into superstars and not enough time figuring out a balanced diet or training our horses.

That said, I have fed magnesium supplements in the past and believe it helped, although that may well be part of the benefit! I fed Freedom Quiessence when he was younger and noticed an almost immediate change in his attitude: he seemed calmer, less reactive and more relaxed. This was at a time when his anxiety levels were very high and I had trouble getting him to focus. While I was feeding Quiessence,  he seemed almost sleepy at times although he never felt sedated.

Over time, I felt that I no longer needed it — I feed a balanced diet and he’s calmed somewhat as he’s gotten older. On days when I want to promote some additional relaxation (for example, at the beginning of hunt season when he’s very pumped), I will still add 1/4 cup of Epsom salts to his feed. It’s a very inexpensive way to add Magnesium to y0ur horse’s diet. If a horse doesn’t want to eat it, I’ll pick up a Magnesium supplement at Costco. Magnesium Oxide is one of the most palatable ways to feed it. I buy capsules and then soak them along with grain.

I’m trying this now with Sheldon. He gets very tense and I know his muscles get sore from the anxiety — I give him a massage after most rides and can feel the difference between the before (when he’s generally pretty relaxed) and after (when he needs the massage to help him release) but it would be so much better if I could prevent the tension to begin with. So far he’s been getting magnesium in his feed now for four days — 3,000 mg twice/day. The footing has been tricky the past few days but once again I think it’s working. He certainly seemed more relaxed today when I rode him and his body felt much less tense after the ride.

Some reports are not as optimistic as my experience. In an article “The Myth of Magnesium Calmers,” Malcom Green wrote that in a small study (numbers were not provided) only 25% of horses responded positively to magnesium.  I guess that in the area of calming agents, that might actually be a pretty good result since I suspect that many have no effect at all, except as a placebo effect on the riders.

Are there Problems with Feeding Magnesium?

Feeding too much magnesium in the short term can cause diarrhea. Over the long term, too much magnesium can interfere with the absorption of other nutrients because it causes food to move too quickly through the gut.

But oral dosing of magnesium is pretty benign. The real problems come with injecting magnesium intravenously. Over the past year or so there have been reports of horses being injected with a magnesium sulfate solution to provide a sedative effect. Although magnesium is not banned by horse show Not only does this break the spirit of anti drugging rules, it can be quite dangerous. While it would be difficult to feed enough magnesium to kill your horse, if it’s injected, it is possible to create a mineral imbalance so severe that your horse may die. Certainly there has been speculation that the show pony Humble, who died at Devon after being injected with an unknown substance, may have received toxic levels of magnesium.

Magnesium supplementation certainly is something to consider if you have a horse that you think could benefit from it, but like any vitamin or mineral it should be used judiciously. More is not always better.

What experiences have you had with magnesium? Do you feed a magnesium based supplement to any of your horses? Do you think it made a difference? Let me know!

3 thoughts on “Magnesium as a calming agent

  1. Liz, any type of mineral supplementation is tricky. If your horse is deficient in that mineral, more than likely you will see positive changes. What people don’t understand about minerals is that it’s not just about meeting deficiencies but about the proper ratios of those minerals for maximum absorption or minimum absorption (in the case of iron, but that’s a whole different story). The recommended ratio for Calcium & Magnesium is 2-1.5:1. Some horses do well with a 2:1 ratio, others do better with a 1.5:1 ratio. However, there is no way of knowing if your horse needs magnesium (or any other mineral for that matter) unless you have your hay/diet analyzed. If you supplement magnesium blindly you can actually make matters worse. There is really no substitute for hay/diet testing. You can then actually supply your horse with what he really needs in the proper ratios & amounts. You can actually learn to do this yourself by taking Dr. Eleanor Kellon’s basic nutrition course “NRC Plus”.
    Which is what I did 5 years ago… and then got hooked on equine nutrition & continued to take every course she offered. Yes, I’m an equine nutrition junkie!

    1. Claire, you are correct. It’s very important to know what you are feeding your horse already so that you don’t create an imbalance. I like using the FeedXL program to help understand exactly what the “grain” portion of my horse’s regime is providing. Hay is trickier. When you are in a barn like ours, where it’s hard to count on a single source, we usually go with regional numbers.

      I also have found it helpful to do a blood panel. My other TB had some symptoms last year that I attributed to Lyme. My vet thought it might also be caused by a vitamin E deficiency and suggested testing. She was right and now he gets a vitamin E supplement. It is much better to know than to randomly supplement.

  2. My OTTB was showing very specific symptoms indicating Mg deficiency. During a freakout over ant bites he actually had a very minor tying up incident, and in general he had muscle tightness and discomfort out of proportion to his workload. I actually discovered even a full day off would leave him more crabby because the work helped relieve some of his muscle tension and tightness. At the same time, he was reluctant to move forward under saddle because of the tightness. He also had what I think were fat deposits behind his shoulder blades – and he’s NOT a horse who typically gets fatty deposits, and it wasn’t caused by saddle fit.
    Starting him on a magnesium supplement made a drastic change in the feel of his body within about 10 days. It did not calm him at all, and in fact a negative side effect was that when his stress issues about going places came out after the Mg supplement he reacted with bucking sprees because physically he could get his head down and round his back to do it, where previously he was too tense to manage that! Overall he is far happier physically, though, and now we can work on his training issues without a physical issue blocking us from doing so.

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