Magnesium supplementation in horses is understudied and underfunded. The NRC guideline requirement is 7.5 grams of magnesium per day for a 1,100lb horse. What if I told you your horse might benefit from additional magnesium? No, no I'm not bankrolling for "big mag". I've seen the results and they are impressive. Sadly, the clinical data is lacking and therefor professionals (vets, nutritionists and hoof care practioners alike) aren't likely to recommend high enough levels of magnesium to achieve the results we are seeing.
So let's dive in. I'm going to pull some relevant peer review journal articles on this topic and discuss. (Again you are not going to find that one magical study that high magnesium levels can improve laminits symptoms in this post. Trust me I scoured the internet and it's not there.)
Magnesium is responsible for over 300 bodily processes, from bone health to enzyme action and even proper nerve function. So what about its role in lamninits?
Let's start with understanding human type 2 diabetes which is similar to EMS in horses. In a healthy body the pancreas produces insulin after a meal, triggering the body to uptake of glucose from the blood stream into cells for energy. In type 2 diabetes insulin is produced but not utilized correctly by the cells, thus impeding glucose uptake.
Check out this YouTube video by Alila Medical Media for a wonderful infographic about diabetes.
We have found in humans with type 2 diabetes that magnesium helps improve the body's sensitivty to insulin. Meaning the body is more efficient at using insulin taking glucose from the blood to the cells.
We know that a loss of insulin sensitivity is associated with EMS and so is an increased risk of lamninits. So, can additional magnesium in the equine diet improve lamninits symptoms?
Yes, but as stated before the data just isn't there yet.
"No statistical significance difference in morphometric measurements, blood variables, resting insulin concentrations or insulin sensitivity in laminitic obese horses."
Chameroy KA, Frank N, Elliott SB, Boston RC. Effects of a supplement containing chromium and magnesium on morphometric measurements, resting glucose, insulin concentrations and insulin sensitivity in laminitic obese horses. Equine Vet J. 2011 Jul;43(4):494-9. doi: 10.1111/j.2042-3306.2010.00302.x. Epub 2010 Sep 29. PMID: 21496075.
So does the story end there? No.
They only dosed at 8.8 gram mag ox/proteinate per day (a little over the NRC guidelines). We are recommending up to 350 grams of Magnesium Oxide a day for some horses; averaging 70-105 grams a day across clientele. Well over the NRC guidelines.
In my time trimming, recommending high levels of magnesium for my clients I have seen horses:
🐴 become less foot sore
🐴 be able to be on pasture and not suffer crippling lamnintis attacks
🐴 remove the blood from acute lamnintis attacks
🐴 strengthen white line connection
🐴 erase white line separation issues
🐴 build better feet
Here is a photo of a recent case of acute of lamnitis thru one trim cycle in early 2023. The only change made was the addition of 70 grams of magnesium oxide to his grain meal every day. You can see the blood in the white line has dissipated.
This is not a miracle cure. Although, in my own personal observations, magnesium supplementation on its own has proven to be effective for healing active lamninits and in my opinion preventing lamninits but it is only one piece of the puzzle.
Thoughtful management practices MUST be adhered to for optimal outcomes. Low sugar diets (eliminating grain rations, watching sugar levels in grasses and limiting sweet treats), increasing movement and regular hoof care.
Lack of magnesium is linked to systemic inflammatory response syndrome (seen in lamnitis attacks). Link of better insulin use in humans with increase in magnesium.
Discussion
Aggregate study of different issues magnesium can cause in the horses body. Lack of magnesium has been linked in horses and humans to body wide inflammation this is what we believe is involved in laminits. Cresty neck gets rock hard, eye sockets become full with inflamed tissue and lamnitis ensues. Are there other bodily issues happening during this time? You bet! Laminitis is affecting the entire hoof we just clearly see one part of it.
There is also a study included linking better insulin sensitivity in humans with an increase in magnesium. It's not a horse study but seeing the similarities in type 2 diabetes with EMS we can extrapolate that there's a good chance it might work for horses too.
Stewart AJ. Magnesium disorders in horses. Vet Clin North Am Equine Pract. 2011 Apr;27(1):149-63. doi: 10.1016/j.cveq.2010.12.009. PMID: 21392659.
Cells responded with increased metabolic activity with increased magnesium - improving insulin resistance.
Discussion
A high magnesium algae product was fed to horses and was shown to improve insulin resistance in a specific type of cell in horses.
Serwotka-Suszczak AM, Marcinkowska KA, Smieszek A, Michalak IM, Grzebyk M, Wiśniewski M, Marycz KM. The Haematococcus pluvialis extract enriched by bioaccumulation process with Mg(II) ions improves insulin resistance in equine adipose-derived stromal cells (EqASCs). Biomed Pharmacother. 2019 Aug;116:108972. doi: 10.1016/j.biopha.2019.108972. Epub 2019 May 17. PMID: 31103825.
Reseach that found a more effective way to measure magnesium levels in the body of EMS horses.
Discussion
This isn't directly related to our discussion but these researchers found a better way to measure magnesium levels in the body specifically in EMS horses which has the potential to pave the way for more precise guidance for magnesium dosage for lamnitic EMS horses in the future.
Winter JC, Sponder G, Merle R, Aschenbach JR, Gehlen H. Intracellular free magnesium concentration in healthy horses. J Anim Physiol Anim Nutr (Berl). 2018 Oct;102(5):1351-1356. doi: 10.1111/jpn.12921. Epub 2018 May 9. PMID: 29740897.
Sadly at this time there is no conclusive evidence that magnesium helps with lamnitis but when you see it in your practice day to day, and the impact it makes on your clients I believe the data is there we just need to find it.
So what do I recommend?
Magnesium oxide or Remission by Animed
If you have a picky eater start with a tub of Remission. Remissions main ingredient is magnesium but it has additional hoof beneficial ingredients. Starting with remission helps acclimate your horse to the taste of magnesium which can be bitter. Feed grade magnesium oxide can be purchased in bulk from most feed mills.
Mag ox is not the most bioavailable form of mag but it is the most economical and most commercially available.
Start with 1-2 tablespoons 35-70g magnesium oxide (1-2 scoops remission) and evaluate. Some horses require much more. I personally have owned an EMS horse who need 10tbs (350g) a day to maintain. Understand that fluctuations in the environment and body will require adjustments to your dose of magnesium.
Bowel tolerance
Though hypermagnesemia is rare it can occur. It usually happens when using magnesium sulfate (epsom salt) at high rates. The biggest symptom is diarrhea. We sometimes reccomend taking a horse to bowl tolerance in an early stage of acute lamninits to prevent damage. This is upping the mag dose enough to cause diarrhea (finding the threshold) and taking the dose just below this. Obviously this is not ideal for your horses digestive tract and I do not recommend using this on old horses, horses prone to diarrhea, coilc or GI upset or foals.
Magnesium is typically fed all year. Adjusting doses during the different seasons. Higher rates in the spring and fall when sugars are higher and a maintenance dose in the winter when on lower sugar hay.
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