The naturalhorsetrim listserv is very fortunate to have Eleanor Kellon, VMD and Linsey McLean aboard.  Dr. Kellon is the technical editor for The Horse Journal.  Linsey McLean is biochemist who formulates VitaRoyal products for both people and horses.

Below are some very interesting posts they have made on the role of magnesium in equine nutrition and laminitis.

From: Eleanor Kellon     <>    
Date: Mon Jun 19, 2000 11:39am
Subject: Re: Battling Laminitis for 18 months

Nora is absolutely right. Need to find the cause of the laminitis and attack that at the same time as the feet are worked on mechanically. Sounds like you have deep seated infection problems - definitely common anyway but in your case may have a stubborn fungal element.

We are currently running a clinical trial on the effectiveness of magnesium in horses/ponies with problems related to chronic founder (grass founder in most cases) associated with obesity, "cresty" necks, abnormal glucose metabolism. This is mentioned briefly on Gretchen's site too. Preliminary results are very encouraging.

By all means check the horse's blood work if there is any evidence of a hormonal/metabolic abnormality such as the abnormally long hair coat and high water consumption of "Cushing's" (pituitary tumor), obesity or normal body weight, but with abnormal fat deposits at tail base and along neck.

Otherwise, have your ration checked for magnesium content and calcium:magnesium ratio. Excess calcium in relation to magnesium is very common, leading to a relative magnesium deficiency. Magnesium is also important for maintaining normal insulin sensitivity. Ration should be supplemented with magnesium to bring the calcium:magnesium ratio down to 2:1. Iodine deficiency is also common and may contribute to hormonal abnormalities. Feed a mineral supplement formulated for horses (there are several good ones out there) or, better yet in many cases, especially if the animal is on a "diet", a protein and mineral supplement such as Triple Crown 30. The hoof is almost entirely protein and you cannot rebuild it without high quality (not quantity) protein in the diet. Would also suggest keeping the feet in boots with a thick bottom layer of cotton or disposable diaper cut to size and saturated with povidone iodine or another suitable white line disease product. This will also make the horse more comfortable while adjusting to being barefoot.

If you correct any contributing metabolic abnormalities, feed correct amounts of mineral and protein to build a healthy foot and combat the infectious agents as well as possible the foot will grow out the diseased portions. it will be a long haul but it CAN be done.

Eleanor Kellon, VMD
Technical Editor
The Horse Journal

From: Eleanor Kellon     <> 
Date: Wed Jun 21, 2000 10:46am
Subject: Re: Re: Several Questions

"My pony grazes 24 hours.  Some one mentioned they thought the trims helped the horses regulate their metabolism better and I am believing it's true."

While I don't doubt for a minute the trims are keeping your pony comfortable, they do not have anything to do with his metabolism. BUT, there is a chance (probably a good one at that) that by restoring proper form and function to the foot, especially as it relates to circulation, that there is much less danger of microemboli (small clots) forming in the circulation to the laminae, therefore helping to "prevent" further problems.

I'd like to take a minute to run through the metabolism and grass founder connection. There are now several studies that have shown that ponies and some horses - whether they have a history of founder or not - have "abnormal" glucose tolerance. What this amounts to is their cells being less sensitive to insulin than other domesticated horses. When they eat a meal high in easily digested carbohydrates (grain or lush grass, especially rapid young growths), their blood sugar and their insulin elevate much higher than a 'normal' horse. This is the same thing that happens in adult onset diabetes in people, at least in the early stages. The problem isn't too little insulin (like in the type of diabetes where people get insulin shots every day), it is that the cells are not sensitive enough to insulin.

I personally believe this is a natural adaptation in the hardy breeds like ponies, Arabs and Morgans that allows them to survive well on sparse vegetation. By being relatively insensitive to insulin, their blood sugars remain more stable, ensuring a constant supply of glucose to critical organs like the brain and heart.

They only get into problems when domestication restricts their exercise (another great way to keep your blood sugars level) and provides them with a diet that is much more sugar-dense than they are made to handle. High insulin (triggered by the high sugar content of the diet) slows the metabolism and shifts it over to fat storing. This is why these breeds are such easy keepers and gain weight quickly on even small amounts of carbohydrate/sugar (there are many different types of sugars in plants and grains, not all "sweet"). Another consequence of this altered metabolism is that the arteries become more sensitive to a chemical in the blood called thromboxane and will go into spasm more easily. This vasoconstrictive (constricted blood vessels) phase of founder is well documented.

The combination of restricted exercise and shod feet, or feet that are improperly trimmed, and a tendency for the arteries to spasm easily is probably a key factor in laminitis developing although other factors, including allergy, could be involved as well.

I mentioned magnesium in an earlier post. Magnesium is the most ignored of all the key minerals and deficiencies are likely widespread. Soil types, grass types (especially legumes like alfalfa or clover) and environmental problems (acid rain) all contribute. Magnesium is involved in literally hundreds of enzyme reactions, including those needed to properly process glucose. It is a well known fact that diabetes are commonly deficient in magnesium and magnesium increases insulin sensitivity. Magnesium is also important for stabilizing cell membranes and membranes inside cells. It will often help alleviate allergic reactions. Finally, magnesium can desensitize the vessels to thromboxane so that they relax and do not go into spasm.

Magnesium (in the form of Epsom salts) is an old folk remedy for founder. Gretchen mentions it on her site. She also mentions it is reported to decrease the size of large crests. Given what we now know about glucose metabolism in ponies and susceptible horses, and the many things magnesium does, it made sense to me that there may be a lot of truth in this "wives' tale". This is why we started The Horse Journal trial.

I'm not free as yet to go into full details because the trial is still running. There is also not magic formula that would apply to every horse or pony in every situattion on every diet. Other minerals may need to be adjusted as well (e.g. zinc is very important to normal glucose handling). However, if anyone is interested in trying magnesium as an aid to reducing crests and/or managing grass founder you can e-mail me directly with:

- age and breed
- history (regarding weight gain, laminitis, any other health problems)
- details of diet (including types of pasture grasses, if known)
- any supplements currently being used

and I will help you with figuring out a dosage to use.

P.S. I also believe that many of these horses and ponies have a low grade laminitis that is not detected until it has reached the stage of a seriously painful problem. You should check the temperature/"heat" of all four feet on a daily basis and remember that a pony or horse just standing around or even walking slowly could look very different if you asked him to trot.

 From: Linsey McLean   <>
Date: Thu Jun 22, 2000 12:49pm
Subject: magnesium

"How wonderful it would be to just trim feet and not have to worry about a fat horse foundering.  Could it be true?"

Not really, there is a lot more to it than that....The internal biochemistry can be the driving force in so many cases, that until you get that stabilized, they just stay inflamed inside. You need help from both inside AND outside.

About the magnesium question... Back in 1977, I did a lot of studies with magnesium and the bioavailability of the different chemical forms of magnesium too, magnesium oxide, magnesium sulfate, magnesium citrate and magnesium amino acid chelate, and their effects in known magnesium deficiency states with symptoms.

Mag without calcium will cause osteoporosis, they have to be balanced. Unfortunately, the old ratios of 2 to 1 don't hold anymore, as we now get only 80% of the magnesium coming through food sources that our grandparents did, and that is if we ate what they did, and we don't...we don't feed what they did either!

Environmental toxins are sequestered in the body as organic acids, which accounts for the huge increases yearly of sales of stomach remedies! They constantly send 911 acid signals from the peripheral tissues, so there is less ability to neutralize acid in the gut. I was awarded a US Patent for my Nutrient Buffer for animals and humans by demonstrating the effects and interference of environmental chemicals on normal biochemistry, and why the current ratios of cations and the use of single cation antacids are obsolete for today's times. We need between a 1 to 1 and an inverted ratio for antacids today.

But if you use an inverted ratio with the chelates, which are more bioavailable, you get osteoporosis...but I do use these special mixes for short times to dissolve splints, ringbone and other undesirable calcifications very effectively, and have for over 20 years.

Magnesium is my favorite mineral because so much can be resolved by adding it into a previously unbalanced feeding regimen. Many feed companies are still neglecting to add it to feeds, or they are using epsom salt because it is cheap!  It is not very desirable for the body though, and this is why it is such a powerful purgative! Studies using animals on a known magnesium deficient diet even did not absorb it as a supplement the body hates it so much that it kicks it out, pronto.. a great laxative but poor supplement!

My feed recipes, on my website, are properly balanced for environmental conditions now, not necessarily SOIL conditions, but ENVIRONMENTAL conditions, which are grossly different!

For supplies, I use both the oxide for the gut and the chelate in my formulations, and they are all balanced for the environment. I have a catalogue full of specialty products and it is also on our web site, so people can use one of several feed recipes and have made very reasonably at a local mill, and top-dress with a supplement most suited for each individual horse. I do not want to provide single elements for previous reasons... can be very dangerous!

Both the feed recipes and the supplements are balanced for the environment., not necessarily the soils alone.

Most environmental and acidity problems exist along the East coast, the Mississippi  River Valley, industrial areas and downwind of industrial areas mostly of the Midwest, and Colorado (with the highest stats on MS in the nation too), and those down lower on the Oglalla aquifer polluted by nitrates.

Least problems are in the high plains states.

I have a live chat on Mon and Thurs when I can, and will this Thurs from 8 to 10pm. You can ask any question about humans or horses etc. The address is on the web site.

For those of you in Michigan, I am giving a free seminar on Environmental Illness in Horses and Humans at Michigan State University expo pavillion sponsored by the Midwest Lipizzan Assoc. at their open dressage show on Thurs June 29, at 7 PM. Everyone is invited to attend.

Linsey McLean
Vita Royal Products, Inc.

From: Eleanor Kellon   <>
Date: Thu Jun 22, 2000 1:27pm
Subject: Re: magnesium

Linsey is absolutely right about increased demands from our polluted environment (which are for minerals other than magnesium too) and that single mineral supplementation can lead to problems in time. However, with these cresty/laminitic horses and ponies, magnesium status has reached a critical level and is best repleted by use of magnesium alone (as Gretchen found out). Multimineral mixes, even with higher than usual levels of magnesium, don't work as well. The systems that control calcium/magnesium/phosphorus levels are only finely tuned to calcium, which is almost always adequate if not excessive in these cases. When we provide a mineral mix that contains calcium in addition to the extra magnesium, the calcium interferes with magnesium uptake. The 2:1 ratio refers to calcium:magnesium in the total diet, from all sources (grasses, hays, grains, supplements, water), not to the amounts in a supplement mix. The correct supplement ratio can only be determined after analyzing the diet. When this is done, 2:1 in the total diet works well for horses.

The time course Gretchen mentioned - three weeks to beginning to see signs of changes in the fat deposits - is exactly what we have found. At that point, usually drop the magnesium dose to half and keep with that for 6 to 8 weeks total (about how long it takes them to lose the fat if not being regularly exercised - quicker if they are being worked) then design an individualized mineral supplementation plan that best matches the hays and grasses the horse/pony is eating. Grain is avoided for these guys (as it should be for any horse that can maintain its weight on hay and pasture alone).

[Gretchen Fathauer’s note: I mentioned that it did not seem that some horses were losing neck crests on dolomite alone. It seemed that the ones who did were "jump-started " on stronger forms of magnesium initially, which included a couple bottles of straight magnesium from the health food store, or a couple of doses of epsom salts, or the magnesium gel marketed for lactating cows, got faster results.]

From: Linsey McLean     <>
Date: Fri Jun 23, 2000 1:06pm
Subject: magnesium

"Linsey, I found your post so interesting and will definitely spend time checking out 'vitaroyal' even though I am too far away to get it. We live close to the sea in Southern Africa on a mixture of limestone, sand, something we call koffieklip (iron stone) and some good soil as well! I have never had a problem with the horses but the goat herd has been a nightmare due to deficiencies in minerals particularly copper and cobalt. None of our commercial licks would be able to supplement for this area unless we made a special order.

"I posted earlier that I am using a supplement which has high mag. less calcium and other minerals + a probiotic, for my ex lamanitic mare. I could not find any straight magnesium that was suitable and was worried about it being given in isolation. I had found out about epsom salts not being a good idea in the long run as a supplement so I stopped it. I am really trying to learn how to help her best. --Sara"

Hi Sara,

I do not know why Eleanor has not been able to get the multi mineral mixes with calcium and the other minerals to work as well as the magnesium alone. I suspect it has to do with either the ratios and/or the chemical forms of the minerals. I started using magnesium singly back in 1977, with individual cases as clinical trials and multiple symptoms of magnesium deficiency, that I could easily monitor. I got results, yes, but I got sooo much better and faster results using the multiple mixes.....when they were balanced for the environmental conditions at the time. I have been following the environmental changes for the last 23 years and adjusting the blends continually, to keep abreast of these changes. There are many people on the healthyhorse list that have been using my environmentally balanced feed recipes and supplements, which contain all the essential minerals, with a great deal of success. They report loss of bloat, better muscle definition, loss of crestiness and better hair coats, with resolution of any number of other health and behavior problems too, and in a relatively short time frame. They are spread all over the US and Canada. You might sign on that list and ask them how they are doing, and the case histories of their horses too. Some of them also join me on my live chat , so you can ask them there as well. the web address is available through the web site. The next live chat is Mon June 26, from 8 to 10 PM EDT.

Linsey McLean
Vita Royal Products, Inc.

From: Linsey McLean    <>
Date: Sat Jun 24, 2000 10:22pm
Subject: magnesium

"….but his neck was not going down on a Tbsp. of dolomite a day. He may need heavier supplementation initially."

Please be aware of the chemical forms of magnesium that you they have different destinations and different effects in the body. It is not such an easy thing as one might think. Also be aware that bone meal and dolomite have more calcium than magnesium in them...the ratios may not be what you're looking for...and both these chemical forms have been found to be highly susceptible to lead contamination, even in the human markets.


From: Eleanor Kellon     <> 
Date: Sun Jun 25, 2000 8:26am
Subject: Re: magnesium

Excellent point about the lead. Aluminum is another possible toxic contaminant, as is iron.

From: Eleanor Kellon     <> 
Date: Sun Jun 25, 2000 1:24pm
Subject: Re: Specific Magnesium Sources??

In response to multiple posts re: types of magnesium and specific magnesium products:

TYPES: In general, minerals that are in an organic form are more easily absorbed than those in an inorganic form. Inorganic forms of minerals are those found in the soil. Organic forms are those found in foods or manufactured to resemble those found in foods.

Epsom salts contains magnesium sulfate - an inorganic magnesium. Dolomite is the inorganic salts of calcium and magnesium. Magnesium oxide is an inorganic form but more easily absorbed than magnesium sulfate. Magnesium gluconate and magnesium asparatate are two examples of organic or "chelated" pure magnesium sources.

Epsom salt magnesium is the least readily absorbed, although some of the magnesium does get taken up by the body. Magnesium oxide is next in line. The magnesium in dolomite is as absorbable as that in magnesium oxide but the problem is calcium and magnesium share some absorption pathways and the body preferentially will take the calcium first. If the diet already has an excess of calcium, some of the absorption pathways will be blocked to both calcium and (as a secondary effect) magnesium. This is why it is best to use a pure magnesium supplement first when trying to correct a serious and longstanding magnesium deficiency. Once the symptoms have abated, you should then switch to a supplement program that contains both adequate magnesium and all other minerals in correct balance. (That is another whole topic!)

THERE ARE NO SPECIFIC STUDIES IN HORSES THAT SHOW HOW EFFECTIVELY DIFFERENT FORMS OF MAGNESIUM ARE ABSORBED. We do know from lots of other mammals and from human studies that organic forms are generally better absorbed. However, if you already have your horse on a program that is working for him, regardless of the type of magnesium you are using, there is no pressing need to change it. It IS important though to make sure that your program is balanced overall for every mineral. If not, deficiencies elsewhere could be induced or worsened.

With very few exceptions, mineral supplements do not "treat" any health problem. What they do is correct an underlying deficiency state that can contribute to certain problems arising. They are very much a way of treating the "whole horse". You are getting the horse's tissues back into a healthy balance so that the whole organism can function normally and at peak efficiency. If horses with certain problems - like a tendency toward grass founder - need more of a given nutrient to stay free of this problem, it is not because that nutrient "treats" the problem. It is because there are underlying conditions/demands in the body that mean this individual needs more of the nutrient to keep his systems in balance. Feeding that nutrient to a horse that does not need it will have no effect or a negative effect, as will feeding more of it than the horse actually needs.

Epsom salts and dolomite should not be considered "bad" things to feed. A better word would be possibly less effective than the other choices.


Since United Vet Equine was brought up, let's start there.

MEGA-MAG: High magnesium comprehensive vitamin and mineral supplement. This provides calcium and magnesium in an approximately 1:1 ratio, higher than the 2:1 we are looking for in the overall diet so it can be considered a high magnesium supplement. 2 oz provides just under 2 grams of magnesium. For horses with a magnesium deficiency significant enough to make them prone to grass founder, this is probably not enough to meet their needs. Feeding more than 2 oz probably won't get the job done either (unless you have a very low calcium hay or pasture) since the calcium goes up when the magnesium goes up (e.g. same problem as dolomite). May need to combine with a little bit of a pure magnesium source (see below). Type of magnesium: magnesium oxide

SERENITY (from Vita-Royal) A calcium, magnesium and trace mineral supplement (no selenium though) with Vitamin E, pyridoxine and thiamine. Gives 5 grams magnesium/oz with slightly less calcium. More concentrated magnesium source than Mega-Mag, but not as comprehensive a supplement (designed to be compatible with other Vita-Royal products without risking overdoses). Best for a low calcium hay/grass based diet. Type of magnesium: Magnesium chelate.

Vita-Royal has a variety of other magnesium containing supplements with calcium:magnesium at just over 1:1 (like Mega-Mag).

Pure Magnesium Supplements:

MAGNESIUM 3,000 (United Vet Equine) Provides 3 grams elemental magnesium per oz serving. Types of magnesium: Mag oxide and mag chelates

E-SE-MAG (United Vet Equine). Provides 6 grams of magnesium plus 4 mg selenium and 2000 I.U. vitamin E per oz. Types of magnesium: Mag oxide and mag chelates.

BIOPLEX MAGNESIUM (Uckele Health and Nutrition). Provides 2.8 grams magnesium chelate per oz.

QUIESSENCE (Fox Den Equine). (Pellet) 5 grms magnesium per ounce from magnesium oxide.

Web Sites:
United Vet Equine:
Fox Den Equine:

These are all reputable companies with quality products. Won't find them in a tack shop or feed store. All sell direct from the manufacturer (which may seem like a bit of a pain but it's a big plus since quality control and stock rotation is much tighter this way.)

HOW TO USE MAGNESIUM SUPPLEMENTS: There are no hard and fast rules because how much you might need depends on the condition of the horse, the type of diet being fed, size of horse, etc.. Acute laminitis and horses that are rapidly becoming cresty are treated differently than subacute cases. Maintenance doses are also different from those for acute problems.

As a rule of thumb, for acute cases or abnormal fat deposits, need anywhere from 3 grams magnesium per day (small pony) up to 12 or more (large/heavy horse, high calcium diet, etc..). Maintenance doses depend entirely on size of horse and type of diet. Maintenance dosing should begin when the acute problem has been corrected.

I wish I could help each of you individually as you need it. To be honest, have done that already for a few but can see it would rapidly become overwhelming. I've been meaning to set up a web site but just haven't had any time to do it yet.

I'll put the cart in front of the horse as it were and do this... Anyone who wants ballpark guidelines for how much to use based on weight of horse, type of problem and duration of problem I'll give you that for a $20.00 fee. All follow up questions and maintenance recommendations free of charge.

For more detailed analysis based on "book values" complete ration analysis as well as the factors above (will get you much closer to the ideal dose), $50.00. Includes specific product recommendations to suit your horse and your diet. I have no ties to any specific companies and will direct you to the most suitable, most economical across the board supplement plan.

Hope this helps...

Eleanor Kellon

From: Linsey McLean    <>
Date: Sun Jun 25, 2000 3:46pm
Subject: magnesium

"I am interested in any other SPECIFIC sources for magnesium. I have read a handful of posts here that are specific in warning against dolomite or epsom salt, but I have not seen any specific alternative magnesium resources suggested."

Dear Jaki,

All of the specialty supplements from Vita Royal Prod. are balanced with higher magnesium ratios for the effects of the toxic environment on our horses, and contain amino acid chelate forms, which are "predigested" forms that are totally non toxic. The beauty of a multimineral mix of these forms is that they do not compete for absorption with each other like other forms do, as they are already bonded to their carrier proteins, and the body uses what it needs and easily excretes the rest. That way, as each body has it's own specific nutritional deficiencies from individual genetics, exposures, seasons of the year, soil and feeds deficiencies, a mix like this is self regulating. No complicated calculations on the part of the owner is required for the best way of satisfying each horse's individual requirements.

A mix using all trace minerals as amino acid chelates costs a little more, but for what it does, however, the benefits far outweigh the increase in cost.

We also do custom blends for individual circumstances for individuals and veterinarians as well as whole farms.

Linsey McLean
Vita Royal Products, Inc.

From: Eleanor Kellon     <> 
Date: Sun Jun 25, 2000 5:17pm
Subject: Re: magnesium

Linsey is correct that supplying minerals in an amino acid chelate form removes problems with their competing for transport mechanisms in the intestine.  When chelated, it is the protein that the transport mechanisms go after and absorb, with the mineral following along.

However, it may not be enough to just get them into the blood stream if calcium levels are being raised at the same time.  There are at least four hormones (PTH, ADH, calcitonin, glucagon) which are sensitive to blood levels of calcium.  As calcium levels rise, the kidney is "told" to excrete more calcium.  Problem is, the kidney does not differentiate between calcium and magnesium so it excretes both.  Presenting the body with both calcium and magnesium at the same time will thus backfire unless the body also needs calcium (which is not the case with many common equine diets and forages - i.e. much more likely to be magnesium deficient than calcium deficient).  This is why it is best to begin correcting the problem with supplements containing only magnesium. The control that calcium metabolism has over magnesium is also why it is important as a second step to get the entire ration as close to perfectly balanced as you can.  Otherwise you will end up needing to feed much more magnesium than you would if you removed the problem (the dietary imbalance) that caused the low body magnesium in the first place.

From: Linsey McLean    <>
Date: Mon Jun 26, 2000 7:00pm
Subject: selenium

Eleanor wrote:

"SERENITY (from Vita-Royal) A calcium, magnesium and trace mineral supplement (no selenium though) with Vitamin E, pyridoxine and thiamine."

"Gives 5 grams magnesium/oz with slightly less calcium. More concentrated magnesium source than Mega-Mag but not as comprehensive a supplement (designed to be compatible with other Vita-Royal products without risking overdoses). Best for a low calcium hay/grass based diet. Type of magnesium: Magnesium chelate.

"Vita-Royal has a variety of other magnesium containing supplements with calcium:magnesium at just over 1:1 (like Mega-Mag)."

Dear Eleanor,

All of Vita Royal's multi mineral mixes contain selenium, including Serenity, which is a blend of our standard Equine Plus Performance mix and a dry form of our Nutrient Buffer and it is designed to be fed by itself, not with other basic multimineral products. It contains two forms of magnesium, amino acid chelate and magnesium oxide.


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