Insulin Resistance in Horses: Not So Sweet by: J. Sinner
Pick up any equine journal the last few years, and you will see an article on insulin resistance. It has become a major syndrome and a very real health challenge for our horse population.
Let's examine this metabolic syndrome, in plain English. Horses who are insulin resistant tend to gain weight very easily. They are the "air ferns" who seem to just look at food and gain weight. Many people try to starve them, putting them on scant and crummy grass hay, dry lot and more exercise. They stay fat. I remember years ago being at a nationally-known trainer's barn and seeing an obese mare waddling round and round on a hotwalker, sweating in the hot sun, for hours. I finally asked if he was trying to turn her into Tiger Butter, and he responded, "that (bleep) is going to stay on that walker until she ovulates!". Yikes, and good luck. This particular trainer was into halter horses and fed straight alfalfa and flax and sweet feed. Big "duh". We have all seen mares, and some geldings and stallions, like this. Cresty necks, fat pads around the tailhead, blubbery shoulders.
So, what's up here? Basically, control of blood sugar is fundamental for healthy life. If blood sugar goes too low, that is called hypoglycemia. Sweating, shakiness, confusion, even death can result. You all know people who are hypoglycemic, who have to eat often or they get all weepy or belligerent. Hyperglycemia or high blood sugar is the other end of the scale. Tom Cowan, MD, writing in Well Being Journal for March/April 2005, states that hyperglycemia is a relatively new phenomenon in human history, and I would submit it is the same in equine history. Physiologically, horses are well equipped to deal with times of drought and food scarcity through the millenia, by using feed efficiently. Times of overabundant food with little exercise are not the norm through either equine or human history. Some equine families tend toward obesity more than others, too. One farrier commented, "they were the survivors", literally selected by nature for their easy keeping qualities, they survived during drought and scarcity while their higher metabolic rate friends were wolf bait from diminished body stores during a hard winter. Enter the human race, who has foisted upon the horse population the "super size it" mentality. "Here, eat like a feedlot steer: high protein alfalfa hay, molasses-laced sweet feed, grains in general.....and lots of all of it, you look really cute when you are all fat and round". The body has lots of hormones developed over history that kick in when blood sugar drops too low, but only two ways to deal with blood sugar that goes too high. Exercise is the first way to deal with it. Exercise drives the sugar from the blood into the muscle cells, which use it as fuel. Production of insulin is the second way in which the body copes. Insulin helps the body remove the sugars from the blood and store it as fat. Dr. Cowan comments that consumption for many years of foods that drive the blood sugar high and chronically exceed the amount of sugar needed by the muscles for exercise, leads to more and more insulin production. Diabetics actually have too much insulin, not too little as the medical community would have us believe. What really happens is, a phenomenon called insulin resistance. The blood sugars are chronically elevated, and the insulin levels are rising, so the cells build a shield or wall around themselves to slow down this flood of excess sugar. The cells close the gates and refuse the insulin, in other words. The situation gets worse, since the cellular sugar levels are low, so the body perceives that as low blood sugar, the person (or horse) has low energy and feels hungry and so eats more. More and more fat is stored, along with fluid retention. We have all seen the "soggy fat" horse that wibbles when it walks, like a Jello mold. This fluid retention can lead to hypertension, circulatory problems (laminitis!) and all sorts of degenerative disease.
Proteins are broken down into amino acids for use in rebuilding the various protein components of bodies. Fats are broken down into fatty acids and used to produce hormones, prostaglandins and cell membranes. Carbohydrates are used for one thing only, and that is energy generation. Carb consumption should be tailored to the activity level of bodies. Marathon runners or endurance and other working horses need carbs, the couch potatoes or pasture ornaments, not so much. It is actually pretty difficult to overeat on proteins and fats, as the appestat tends to shut down. Merely cutting down on carbs will result in blood sugar lowering. High carb foods also tend to be acidic in the ash residue they leave, and as Regan has reminded us so many times, diabetes or insulin resistance is a disease of over-acidity. Cutting grains way down or out completely is where he usually starts, in treating diabetic humans, and in dealing with insulin resistant horses as well.
Minerals are also an important factor. Again according to Dr. Cowan, the minerals chromium, zinc and vanadium are important in insulin production and absorption. Without vanadium, sugar in the blood cannot be driven into the cells. Chromium regulates carb metabolism and proper function of insulin receptors. Zinc is a co-factor in insulin production. Magnesium is important in blood sugar regulation, and for thyroid support as well. B6 is a vitamin that is essential for carbohydrate metabolism. High levels of vitamin A are important, since diabetics are unable to convert the carotenes in plant foods into vitamin A. Vitamin D is essential for insulin production as well.
So, how does all this translate to management of our IR horses?
*Tailor grain feeding to activity level. The less grain you can feed, the better, most relatively inactive mature horses don't need grain at all. Even growing babies should be limited on grain meals, as blood sugar spikes have been proven to affect bone and joint development in a negative way. Small amounts of grain, spread over several feedings a day, work best for all horses who get grain. For sure stay away from the sweet feeds. Use Dynamite Pelleted Grain Ration or a plain dry cob (corn, oats, barley) mix. If the horse is already IR or laminitic or showing tendencies, grain is verboten.
*For topline and healthy weight gain, substitute HES Pellets (our organic whole extruded soybean pellets) for healthy protein and fat, without the carbs. Most horses do well on just a few cups of PGR if they need grain at all, and then a cup or two of HES Pellets, depending on weight and activity levels. We have some Dynamite show/performance horses who get HES and their supplements only, no grain, especially if they tend toward EPSM.
*Test your hays for NSC (non structural carbohydrates). For problem horses, try to stay at or below 10% NSC. http://www.equi-analytical.com/ is a great testing resource. Many of the newer species of grass hays are extremely high carb, great for fattening cattle and other livestock, but the literal kiss of death for many horses. One researcher calls perennial ryegrass, "the quintessential founder fodder". Bermuda and timothy are lower in carbs than many other grasses. Bluegrass, orchardgrass, rye, fescue are innately higher in carbs. Even weather plays a part. Cold sunny weather causes the grasses to store more sugars in the bottom 3" of the plant, as they can't use the sugar for growth. Spring and fall pastures and hay crops can be leaded and deadly! Cloudy days will drop the sugar levels in the plants, as will active growth during hot weather, especially when pasture is being fertilized and irrigated. Don't graze or mow pastures lower than about 4", for insulin resistant horses, as most of the sugar is in the plant stems. There is huge fallacy in grazing the IR horse on the "down to the nubs" fields, they are actually higher in sugars. Grazing muzzles are a good thing, if the horse needs exercise but needs to be limited in grass intake. http://www.safergrass.org/ is a great website for more info on which hays and grasses are safer for horses with this metabolic syndrome. I found a great resource for grass seed in CO at the Horse Expo last week, they can custom mix virtually any blend from dozens of grass seed varieties. Sharp Bros. Seed Co is at Buffalo.GXY@SharpSeed.com or 970-356-4710 in Greeley, CO.
*If you must feed higher carb hay, such as first or third cutting, or the higher carb varieties, soak the hay. Soaking for an hour in hot water, then draining and feeding, will siphon off about 50% of the sugar. Buy rained-on hay, if you can, as long as it is not moldy. Rain between cutting and baling takes out a lot of sugar.
*Provide available minerals and vitamins. Our TNT is made to order for IR horses. It contains regular Dynamite for Horses, Free and Easy for pain and inflammation, Excel for enhanced digestion, HES Pellets for fat and protein, Izmine for trace minerals, and Easy Boy for extra magnesium which enhances thyroid function and helps with circulation as well. Add chromium, in the form of high chromium yeast (GTF chromium) or an amino acid chelated chromium. 1000 mcg or more chromium is usually needed for these horses. Added vanadium is good as well. Ester C or Hiscorbadyne is great as an antioxidant, and C acts as a natural anti inflammatory as well, especially important if your IR horse tends toward laminitis. I also like a little Breeder Pac to help with pituitary function, and even some DynaLite if you have low thyroid going on. Even adding a little cinnamon to the feed has been shown to help normalize blood sugar levels.
*Balance digestion and build B vitamins in the gut with DynaPro. Stable gut flora goes a long way toward limiting and controlling laminitic tendencies.
*Consider adding some fats for these horses. Our HES contains the whole organic soybean which of course adds soy oil, in the original and unfractionated form. Black Oil Sunflower seeds, a cup a day or even less, will add more fatty acids. According to Dr. Cowan, diabetics lack the enzymes to make special long-chain fatty acids from the essential fatty acids. I don't know if research to this effect has been done on IR horses, but it makes sense to me that similar factors might be at work here.
*Be really, really careful with vaccines and chemical dewormers on IR horses. They tumble over the edge into laminitis and founder so easily. I don't vacc or deworm my IR mare at all, she gets our usual arsenal of Herbal Tonic and Excel to help with parasite control.
*Exercise them, let them live outside instead of in a stall, and manage feet for optimum circulation: Keep them barefoot if at all possible, or at least shod for easy breakover and maximum heel expansion.
*Address "sweetness of life". Just like with diabetic people, metaphysical causation can enter into health problems big time. Is the IR horse sad? Is he or she rejecting the sweetness of life, wanting a new owner, another job to do, needing more attention, mirroring issues in your life? Some judicious work with Relax or Tranquil, listening to your intuition about the horse's needs (or yours!) or consulting an animal communicator can be a big assist to balance.
With careful management, our IR horses can live long and healthy lives.