I came upon this article about magnesium. To be honest, I haven’t paid attention to how much magnesium my horses are getting…
…but Wrigley sure fits into the model for a deficient horse.
Hmmmm.
I am going to research my local feed store and see what they have in bagged magnesium supplements. It is said to be inexpensive and easily excreted.
Please read the below articles. I had no idea!
Original article linked here.
Magnesium: The Mineral Superhero
Very few people are aware of the enormous role magnesium plays in a horse’s body. After oxygen, water, and basic food, magnesium may be the most important element needed to maintain health. It is vitally important, yet hardly known. Magnesium is by far the most important mineral, regulating over 325 enzymes in the body. Magnesium supplementation has been shown to improve performance and allow human athletes to reach exhaustion later in their exercise routine. It increases oxygen delivery to muscle tissue; it promotes muscle strength, endurance and relaxation. Magnesium also activates enzymes necessary for the metabolism of carbohydrates and amino acids which lead to protein synthesis.
Magnesium is often the most neglected mineral in horse feeds. Spring grass is typically deficient in magnesium due to the fast growth rate and at this time of year many horses seem hotter and more difficult to ride. Owners often attribute this to too many carbohydrates in the grass. While this may be part of the story, what is often overlooked is that these horses may be deficient in magnesium. Magnesium deficiency has varying effects on the horse population. Some horses do not suffer any signs while others are almost unrideable due to their apparent silliness and hyperactivity. Adding magnesium to their diet may have a dramatic calming effect. To understand why magnesium affects the horse in a calming manner, it is important to know what is happening in your horse’s body on a cellular level when there is a magnesium shortfall.
Calcium and magnesium work closely with each other. Calcium needs magnesium to assimilate properly however magnesium does not need calcium. Calcium is in charge of contracting the muscle and magnesium looks after the relaxation or release of the muscle much like a gas pedal and a clutch work together. When a muscle cell is triggered, the cell membrane opens, letting calcium in and raising the calcium level in the cell setting off a reaction and the muscle contracts. When the contraction is done, the magnesium inside the cell helps to push the calcium back out of the cell releasing the contraction. This happens very rapidly. When there is not enough magnesium in the cell, calcium can leak back in causing a stimulatory effect and the muscle cannot completely relax. This can put the body into a continually stressed state. Low magnesium makes nerve endings hypersensitive thus exacerbating pain and noise. Magnesium is required for proper nerve and muscle function.
The use of magnesium today is often incorrect. One reason is this: Calcium needs magnesium in order to assimilate into the body. However, when too much calcium is consumed, it inhibits the body’s ability to absorb and utilize magnesium efficiently. To maintain proper levels in the blood, the body will borrow magnesium from bones and soft tissue to make up for the shortfall in order to assimilate the calcium. Over time, this creates an accumulative negative reaction in the body that actually triggers the body to release adrenaline adding to the excitatory behavior we see in deficient horses. To correct a deficiency, magnesium needs to be offered by itself, not with calcium. Only approx 1% of magnesium is stored in the blood, the rest is stored in soft tissue and bone and the body is very efficient at maintaining that level in the blood stream to facilitate organ function. This is why blood level magnesium tests are rarely indicative of an animal’s true magnesium status. A horse would be severely deficient and would be very ill by the time a blood test would indicate a shortfall.
Horses with magnesium deficiency may have all or only a few of these signs so it is important be aware of them. They may be borderline and only exhibit signs during competition or stress. For instance, horses with magnesium deficiency often have very sore tight backs in spite of excellent saddles and pad, proper fit, conditioning and training. They don’t respond well to chiropractic adjustments and massages or these treatments don’t last more than a couple days and the tension and soreness return. They often resent or even act afraid of being touched leading the owner to ask themselves, ‘Is someone abusing this horse when I am not around?’ Their response to outside stimuli is over reactive and they tend to become fractious, worried, fearful or resistant to training.
Other signs:
- Unable to relax physically or mentally
- Muscle tremors, twitches, flinching skin, or all over body trembling especially after exertion (not related to outside temp)
- Body tension
- Does not tolerate long periods of work– often becoming more excited instead of working down
- Has difficulty with collection or picking his back up under saddle, moves hollow
- Random spooking, running through the bridle, inconsistent from one ride to the next
- Angry about being brushed, blanketed or touched or palpated on either side of spine
- History of tying up
- Fatigue
- Painful heats in mares
- Bucking or rearing 20-30 minutes into a ride for no apparent reason
- Requires long periods of lunging before being able to focus on work
- Would be described as ‘thin skinned’ or over sensitive to sound or movement
- Massage and chiropractic adjustments do not have lasting affects
- Teeth grinding
- Irregular heartbeat or pounding heart- endurance horses often experience this at vet checks
Magnesium is assimilated quickly in times of stress, such as traveling or heavy training. Horses lose magnesium through sweat and urine. Many performance horses can become deficient as the season progresses as they are using the available magnesium more rapidly due to stress, travel and competition. Horses with low magnesium status will often crave salt, which exacerbates the shortfall. Calcium-rich diets can create an imbalance.
These horses are often difficult to work with, so riders tend to over exercise in an effort to manage behavior. They are worked harder and for longer periods of time in an effort to wear them down which only adds to the shortfall thus creating a vicious cycle. This causes more sweating and muscle cramping while contributing to fatigue, soreness, post competition pain and a negative association to work. Behavior gets worse with more work and exposure to stress, not better. Subsequently, horses begin to resent the show arena often developing gate issues.
There are many factors that affect magnesium absorption and utilization. Working horses require 10-30% more magnesium for light to moderate exercise, respectively, due to sweat losses. Horses who sweat heavily will lose magnesium at a more rapid rate as well.
Magnesium toxicity is rare because excess is naturally excreted. Magnesium should be split between morning and evening feedings to increase absorption and decrease its occasional laxative effects. Once a horse becomes low on magnesium, it is very difficult for them to catch up without supplementation.
What kind of magnesium should I use? There are injectables, oral supplements and transdermal applications. The most popular is oral magnesium oxide. It is the least bio-available form of magnesium but it is the most available and inexpensive to feed. Some horses do not like the powdery texture so picky eaters may turn up their noses to it. It can also act as a buffer in the horse’s stomach which can help horses who tend to develop ulcers. There are many oral forms of magnesium; the best form of which is Di-magnesium malate. It is highly absorb-able, bio-available and has the least potential laxative effect. Horse owners need to be aware that magnesium is in different forms such as citrate, oxide, ascorbate, which is the secondary ion. Horse owners should avoid magnesium sulfate because of its laxative effect. We recommend feeding 6 to 10 grams daily or to bowel tolerance, for working horses exhibiting mild to moderate signs of magnesium deficiency. Horses showing severe signs of deficiency respond may require more. Every horse is different and will have its own individual maintenance dose. This will also fluctuate depending on times of stress, showing, weather and pasture content. When signs of deficiency begin to subside, the dosage can be tapered off.
Transdermal magnesium (delivered through the skin) is an efficient way to deliver magnesium to muscle tissue as it bypasses the digestive system all together and can be taken up by the muscles rapidly. Transdermal application can be very therapeutic prior to athletic competition especially for the nervous horse and also post work out helping the body to recover and relax muscles. It is available in sprays, lotions and a magnesium chloride salt form that is dissolved in warm water, sponged on the horse and rinsed off after 20 minutes. This is the most economical of choices.
How do you know how much magnesium your horse is getting? It’s very difficult without analyzing every bale of hay. Many feed supplements only give you a percentage of mineral content, not a gram total. One thing you can do to insure your horse is not deficient is to familiarize yourself with the signs of possible deficiencies in your horse. If you think you may have a shortfall, it’s a very safe mineral to give in any case. Toxicity is extremely rare. Horses with reduced kidney function should not be supplemented with magnesium without vet supervision. Make sure your horse has access to water.
Disclaimer: The information in this article in not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information. We encourage you to make your own health care decision for your horse based upon your own research and in partnership with a qualified veterinarian.
THIS ARTICLE WAS PAID FOR BY JEFFERS VET…BUT HAS GOOD INFORMATION
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Magnesium
Is your horse nervous?
Is he highly anxious in numerous situations?
Do you wish there is something you could do?
There might be an easy fix…
One of the most common signs of magnesium deficiency is extreme nervousness.
Read on below to find out more about this essential mineral…

Magnesium (Mg) plays a number of important roles in your horse’s body.
In his muscles, it attaches to ATP so that the ATP can be used by the muscle cells. If the Mg is not present, the ATP cannot be used, and the muscle would not be able to generate energy to carry out any functions.
It also plays roles in your horse’s blood, as well as acting as an activator for many enzymes throughout the body. It is necessary for many of the enzymes that work with ATP.
Almost 60% of the Mg in your horse’s body is in his skeleton, while another 30% is found in his muscles. The other 10% is found in various areas, including the blood and liver.
Mg is one mineral that the absorption of is not highly influenced by other minerals. Calcium, phosphorus, potassium, and aluminum all have little, if any effect on the absorption of Mg. It is also good to know that neither oxalate or phytase affect the absorption either.
Likewise, exercise appears to have little effect on the absorption rate.
Dietary Sources
Mg that your horse gets naturally from his diet is absorbed at a rate of about 40-60%. With most feeds containing around 0.1-0.3% Mg, it can be hit or miss whether or not a horse meets his daily needs.
However, inorganic forms that are often supplemented — Mg oxide, sulfate, or carbonate — appear to have a higher absorption rate at around 70%.
Magnesium Deficiency in Horses
Horses that are deficient in Mg show a variety of symptoms, including:
- Nervousness/Flightiness
- Muscle tremors
- Ataxia (incoordination and unsteadiness)
Diets low in Mg also cause mineral clots to form in the aorta, the main blood vessel that carries blood from the heart to the body.
Magnesium Toxicity
Mg toxicity has not been studied in the horse. However, at normal dietary concentrations of varying Mg sources, it appears that there is little likelihood of toxicity being a problem.
The only time toxicity might be an issue is if Mg sulfate is used as a laxative to clear a blocked intestine. If it is overdosed, it can cause a toxic reaction, which has symptoms of kidney insufficiency, calcium deficiency, and intestinal damage.
Supplementing Magnesium to Horses
Many horses are supplemented Mg to try to calm them. There are a number of products on the market, including Ex-Stress:

Sold by Jeffers Equine
Another popular supplement for Mg is Quiessence. These (and other commercial Mg supplements) are all good magnesium supplements, and work for many horses.
If you don’t want to spend that much money, another option is simply to buy magnesium oxide from your local feed mill. It is straight Mg oxide, which is what is the main ingredient in most Mg supplements anyways.
This usually is sold under the name of MagOx or FeedOx, and is a supplement that cattle owners use to mix into their cattle rations.
As a result, its usually not displayed on the floor, and you will have to ask an associate for it.
You’ll also probably have to specify that you want a cattle product, as the associate will probably be confused if you tell him or her that you are buying it for a horse.
In my experience it comes in a non-descript brown bag, usually in 50 pounds. Last time I bought it (sometime last year) it cost me $12 for the bag.
The great part about using MagOx is that it is so inexpensive…it is fed at a rate of tablespoons per day, so that bag lasts forever!
To use it as an insulin resistance treatment, supplement 3 tablespoons/day for the first month, then reduce that to 1 tablespoon/day for maintenance.
I supplement all my horses with Mg, as it is so inexpensive and it is thought that many horses today are probably Mg deficient to some degree.
OUR JANUARY 2017 BUCKET FUND: THE OLD AND FORGOTTEN HORSES of the Golden Carrot
JANUARY 2017 BUCKET FUND! In honor of Mama Tess, we are offering the MAMA TESS’ OLD AND FORGOTTEN FUND supporting the very old and forgotten horses who landed at The Golden Carrot. You can read their story here. Please help if you can. The Bucket has $915. Our goal is $2640.
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This is late 20s early 30s, gorgeous Glory!
