Supplemental Magnesium for Horses

A few years ago, I had the opportunity to take Dr. Eleanor Kellon’s NRC (National Research Council) Plus and Nutrition as Therapy courses as part of my equine acupressure program.  I learned a great deal from the courses and would highly recommend them to anyone interested in equine nutrition.

In the NRC Plus class, we learned how to balance our horses’ forage-based diets by using a hay or pasture analysis.  I have to say, at the time, the prospect of balancing a diet was quite intimidating.  It involves a lot of math, which is definitely not my forte!  With a lot of time, practice, and patience, I learned to do it though.  And I still do it for all five of my horses every spring and fall.

One of the several minerals I now supplement to all my horses is magnesium, a major mineral needed by all horses.  I’ve found that the magnesium levels within my pasture and hay (which we cut and bale on our property) are adequate, but when it comes to the Calcium: Magnesium ratio, which should optimally be 2:1, there’s not enough magnesium.

I would venture to guess that many horses’ diets are out-of-whack when it comes to the Calcium: Magnesium ratio.  Especially horses that consume very much alfalfa, which is high in calcium.  The only way to know for sure is to have your forage and feed analyzed, which many people may not want to mess with.  But if you have performance horses, or a horse with a specific condition, such as insulin resistance, founder, or heaves (which can be helped by supplemental magnesium), you may want to look into it.  You can even hire an equine nutritionist to do the work for you.

According to the research I’ve done, a deficiency in magnesium (which, interestingly enough, mirrors symptoms of excess Calcium–go figure!) can include these symptoms in horses:

  • irritability;
  • hypersensitivity;
  • muscle twitching or spasms;
  • anxiety/ nervousness; and/or
  • gait disturbances.

My 24 year old mare, P.K., displayed irritablity and hypersensitivity (to the point of dipping down or moving away when you ran your hand down her back) for many years.  It wasn’t until I put her on a balanced diet, which includes added magnesium, that those symptoms went away.  I’m amazed at the difference in her now.

I buy magesium oxide (as well as other individual minerals) from a company called Horsetech.  It looks like this.

Magnesium Oxide

This particular magnesium oxide contains 60% of elemental magnesium.  I feed anywhere from 5-11 grams of it depending on what each horse needs.  I measure it with this little gram scale.

I mix up a week’s worth of minerals for each of my horses and put them in extra-large pill containers.  I’ve found these to be nifty little time-savers.

Then I mix half of the minerals in their morning feed and half in their evening feed.

Even my pickiest eater, Hershey, usually eats his magnesium and other minerals without a problem.

Of course, I’m not recommending that everyone rush out and buy a magnesium supplement for their horse, but if your horse has any of the magnesium deficiency (or excess calcium) symptoms or has one of the specific conditions I listed above that might be helped by supplemental magnesium, it might be worth talking to your vet or an equine nutritionist about.  I’ve found that some vets aren’t extremely knowledgeable when it comes to nutrition, but there are a few out there who are.  I’ve learned that sometimes you just have to get out there and learn things for yourself though.  I’m definitely glad I did!







Hi! My name is Casie Bazay. I'm a mom, a freelance writer, and a certified equine acupressure practitioner.

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6 Responses

  1. allison says:

    I’ve been giving my horse a Magnesium supplement since she came to me. It has worked wonders for her anxiety.

  2. There is a better way to supplement your horses with magnesium. Transdermal Magnesium Oil. It’s 100% absorbed through the skin. This is wonderful and it bypasses the gut, so no loose stools. Magnesium Oxide is the poorest and cheapest form of magnesium but more importantly its poorly absorbed. In people, it’s about 4% absorption

    • Casie says:

      Hi Jeannine, Thanks for sharing. Since writing this particular post, I’ve learned more about magnesium and which forms are better utilized by the body. Mg oxide was the form recommended in the equine nutrition courses I took.

      • Katrina turnage says:

        So Casie, which form of mag do you use now? I’m confused. Started using mag oxide then switched to now using mag D Malate, and use the mag chloride as a body soak when needed.

        • Casie says:

          I don’t feed individual minerals anymore for the most part. I’m currently feeding a multi-vitamin/mineral which includes magnesium. I also feed flax which is high in Mg as well.

  1. November 16, 2013

    […] while back, I did a post on Supplemental Magnesium for Horses.  Magnesium is one mineral that I always make sure to supplement (especially since my pasture and […]

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