Managing the Metabolic/Cushings/IR horse
Submitted by: Melyni Worth
Phone: 540-294-3003
Email Address: melyni(at)nutrelief.com
Date Added: 6/15/2010
Managing the Metabolic Syndrome/Insulin Resistant or Cushing’s Horse
As we go into spring and the grass is growing, many people are worried about their Metabolic/IR or Cushing’s horse out on pasture. The big question is will he get laminitis and subsequently founder?
Why do some horses react this way to eating lush green grass that they evolved eating? Why does something so natural cause so many problems?
Laminitis is a term which means literally inflammation of the laminae.
What are the laminae?
Within the foot, the horn of the front wall is attached to the front of the pedal bone by a series of intertwining ridges and channels. The ridges are very fine and have a leaf like appearance when seen under a microscope, hence the name laminae. Laminae provide a way for the horn to closely and firmly attach to the front of the pedal bone, supporting the bone while allowing the hoof wall to grow down from the coronary band. The horse stands supported between the pull of the deep flexor tendon attached at the base of the bone, and the attachment of the bone to the wall of the hoof. The laminae are key to this attachment. Without the hold of the laminae and horn, the bone would be pulled back and down by the deep flexor tendon and the weight of the horse would push the bone through the sole of the foot. This is what happens when a horse founders. The laminae become inflamed and try to swell, the strong attachment of the bone to the hoof wall is lost and the horn no longer holds the bone in alignment. The deep flexor tendon pulls from the base of the pedal bone and the bone rotates to point down, causing the weight of the horse to push the bone onto the sole and in some cases out of the bottom of the foot.
This is a very painful, serious situation, which is almost always preceded by a bout of inflammation of the laminae called laminitis. Untreated Laminitis can result in founder. Any time a horse gets laminitis it should be taken seriously.
What causes laminitis?
Many things can upset the delicate arrangement of bone and horn tissue. The laminae have an enormous network of capillaries within them that keep the tissues fed and oxygenated. The arterioles feed blood into the capillaries and the veins collect it afterwards to send it back to the body. However, the horse has a special arrangement within the circulation of the foot. There are special little connecting valves between the arteries and the veins which allow blood to bypass hoof tissues and go straight back to the body without delivering the precious nutrients and oxygen. If anything happens to upset the circulation within the foot then the blood gets shunted back without going through the foot capillaries and the hoof tissue and deprives these tissues of nutrients and oxygen. When this happens, the tissues become inflamed, try to swell and can even die.
Toxins present in the system can cause this to happen. Toxins from bacterial infections, retained placentas, colic and from the environment can all cause laminitis to occur, but these aren’t the causes we are going to discuss in this article. Laminitis from these causes is equally devastating, but the preventative measures you would take are different.
The laminitis we are referring to affects horses that appear otherwise healthy (no infection, no colic), but get laminitis when eating grass or for no apparent reason.
Research has shown that these horses are getting laminitis from the insulin circulating in their system. Many of these horses are insulin resistant and have very high levels circulating as a result , which triggers the inflammation.
Why do horses get high insulin?
Insulin is a hormone created in the pancreas which the body uses to encourage muscle and other cells to absorb glucose from the blood stream. Glucose comes from digestion, especially if the food contains a lot of sugar or starch. As food is digested, sugar is absorbed by the walls of the GI tract and enters the bloodstream. As sugar enters the bloodstream, the body releases insulin to trigger the muscle cells to absorb it. However, sometimes the muscle cells don’t want it and don’t respond properly, so the pancreas reacts by putting out more insulin to get the glucose out of the blood stream. This is what we mean by insulin resistant - more insulin is needed to force the muscle to take up the glucose.
Once the level of insulin gets high enough, it causes problems with the basement membrane, the main ‘glue’ of the laminae, and the cells start to get inflamed. Sometimes it’s just a small inflammation, not enough to cause the whole foot to fail, but enough that the hoof-bone adhesion to weaken and begin to stretch. If the horse has repeated attacks of small minor inflammations, it can gradually weaken the entire structure. Then, one day a relatively small attack causes the whole thing to fail and the horse has an unexplained founder episode for no apparent reason.
What can you do to prevent laminitis?
The key is to reduce insulin. Remember, insulin responds to sugar levels in the blood stream of the horse like a diabetic person. You have to eliminate sugar and starch from the horse’s diet, and reduce or eliminate the components of the food that contribute to sugar levels. Follow these guidelines – together, these components are called the low glycemic diet:
• NO whole grains, oats, barley, corn or molasses.
• NO spring grass. Spring grass produces sugar from CO2, water and sunlight. While grass is young it has high sugar levels, especially in the evening after a day of photosynthesizing in the sun.
• Try to feed a hay only diet - very sensitive horses will need to have their hay soaked to remove the natural sugars found in the hay.
• If your horse needs extra calories over and above hay to maintain their weight, then use a feed that is not just low in starch, but low in NSC (Non-Structural Carbohydrates). NSC is the scientific term for overall sugars and starches. A suitable feed for Insulin Resistant horses will have an NSC of less than 15%.
Horses on low glycemic diets usually get little or no commercial grain or processed feed. This means they may sometimes have mineral deficiencies since they are not getting any extra mineral or vitamins over and above what the hay provides. At this time, the horse may benefit from mineral supplementation. Mineral imbalances have a large part to play in Insulin Resistance, though the full details and methods are not fully understood. We do know that certain minerals, if supplemented, seem to prevent laminitis and enable the horse to safely eat a bit more grass than without them. These minerals are Magnesium, Chromium, Copper and Zinc – try to use a concentrated or fortified source so you do not have to feed much of it to supply sufficient minerals.
In summary…
If your horse is Insulin Resistant, has Metabolic Syndrome or Cushing’s, if he gets growth rings on his feet when turned out on grass, and if he has ever had laminitis, this is what you need to do:
∗ Reduce or even eliminate grazing. A muzzle allows the horse to move about (exercise is very important in treating or preventing this condition), but reduces the amount of grass he can eat.
∗ Take him off any and all whole grains. If the horse needs feed, use a feed with low NSC.
∗ Feed hay, which might have to be soaked if he is very sensitive.
∗ Use a good vitamin/mineral supplement that provides all the vitamin/mineral requirements. Make sure it has enough copper and zinc. NRC requirements for copper are 20mg/100kg bodyweight per day. Requirements for zinc are 80mg/100kg bodyweight per day. Products where the concentration of minerals is high enough that you can feed smaller amounts of feed are better. Products such as Foxden Equine’s LinPro and ADM’s Metabolic pellets are ideal. Pace-Maker Fat & Fiber feed is a very good low NSC, mineral fortified feed.
∗ Increase Magnesium intake to 10-20g per day. Chromium supplementation also helps. Though there is no known requirement for horses, work in swine indicates that 4-5mg day seems to be the most effective range. Look for a product that contains both Magnesium and Chromium. An example is Foxden Equine’s Quiessence.
∗ Exercise is paramount in the treatment and prevention of Insulin Resistance, so above all, get the horse moving. Walk, lunge, pony or ride. Any way you can get the horse moving is better. Don’t leave the horse shut in a small, dry lot and think that starvation is enough. Get them out and moving. It’s better to turn out in a big pasture with a muzzle than to stand them in a tiny dry lot.
With the right diet and management, you can prevent this devastating condition from occurring.
Melyni Worth, PhD owns Foxden Equine, a nutrition company in the Shenandoah Valley which produces nutritional supplements for horses and ponies. Questions on equine nutrition can be sent to Melyni via the website, www.foxdenequine.com.
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