| Here's a quick test. Ready? | | | | or bad weather, he will start gaining weight if his feed |
| * Does your horse sometimes seem sluggish, gain or | | | | is not cut. Third, exercise increases the cells sensitivity |
| lose weight easily, or lose muscle over his top line but | | | | to insulin, even in IR horses. This is why we are able to |
| maintain a cresty neck? | | | | give feeds with slightly higher NSC levels to |
| * Does he stock up easily or sometimes seem prone | | | | performance horse in work. |
| to hoof soreness or abscesses? | | | | Obesity |
| If your horse displays any of these symptoms he | | | | Obesity is a major trigger for IR. It is a sign that the |
| could be insulin resistant (IR), a condition that has | | | | carbohydrate intake of the horse has been higher than |
| recently come to the attention of many professionals | | | | his need for a period of time. Excessive carbohydrate |
| and owners in the horse industry. | | | | intake will increase the production of insulin, and |
| Insulin is produced by your horse's pancreas and is | | | | continued exposure to high insulin levels can decrease |
| needed to move glucose out of the blood and into the | | | | the cells' sensitivity to it. Obese horses are also less |
| cells where it can be used for energy. Some horses | | | | likely to exercise on their own. |
| are genetically predisposed to develop a condition | | | | Stress |
| where their cells do not respond properly to insulin so | | | | Last but certainly not least is stress. Horses are |
| glucose metabolism is impaired. However, not all | | | | fight-or-flight prey animals and, as such, tend to release |
| horses that have this predisposition will develop insulin | | | | glucose quickly into the blood if frightened. In a natural |
| resistance. Triggers that can case this condition to | | | | environment, a frightened horse needs this glucose to |
| manifest include high-carbohydrate or high-fat diets, | | | | either run away or fight. These activities quickly |
| mineral deficiencies, lack of exercise, obesity, and | | | | consume the glucose in the blood. Domestic horses |
| stress. Let's look at each of these factors. | | | | under chronic stress have a similar fight-or-flight |
| High-Carbohydrate Diets | | | | response and will experience the continued release of |
| Carbohydrate levels in feeds are best evaluated by | | | | corticosteroids. This causes glucose levels to stay high |
| looking at the non-structural carbohydrate (NSC) levels. | | | | and will keep triggering the release of insulin. The high |
| Unfortunately, these levels are not listed on most feed | | | | levels of circulating insulin are the cause of many of |
| bags but they can be obtained for most grains and | | | | the symptoms we see in constantly-stressed horses. |
| hays at Some experts feel that a horse with IR should | | | | To avoid this situation, get to know your horse and |
| have a total diet that is less than 10% NSC. However, | | | | determine what stresses him. Avoid putting him in |
| this low percentage is difficult to achieve as few feeds | | | | these situations whenever possible. If you simply can't |
| or hays have less than 11% NSC and they must be | | | | avoid a known stress, be there to support him. A |
| soaked to leach out the sugars to get levels this low. I | | | | horse that knows he is loved and appreciated can |
| feel most performance horses that are not showing | | | | handle much more stress than one who is treated like |
| serious symptoms, such as laminitis, and are still being | | | | a tool. |
| worked regularly can handle NSC levels between 10% | | | | Discovering Whether Your Horse is IR |
| and 15%. | | | | To find out if your horse is IR you can have a simple |
| High-Fat Diets | | | | blood test done that measures glucose and insulin |
| IR horses vary greatly in the amount of fat they can | | | | levels, and then takes a ratio of glucose mg/dL divided |
| handle. In general the longer the condition has been | | | | by insulin mU/L. If this number comes out over 10 then |
| active the less fat the horse can metabolize. Long | | | | you have nothing to worry about. If the number falls |
| standing IR will cause damage to the horse's liver as | | | | between 4.5 and 10 your horse is IR but is still |
| the body tries to store the extra circulating glucose in | | | | compensating. If your horse falls in this category, you |
| the liver. This causes a fatty liver syndrome and the | | | | need to change his management (in terms of the |
| liver will swell, which blocks the bile ducts. Bile is needed | | | | factors discussed above) to prevent his condition from |
| for fat digestion and if flow of bile into the small | | | | worsening. If the number is less than 4.5 then your |
| intestine is blocked, fat will not be digested. In addition, | | | | horse is already compromised. If you do not |
| the presence of fat will interfere with the digestion and | | | | immediately change his management, he could be at |
| assimilation of other important nutrients. I often suggest | | | | risk for laminitis. |
| the herb milk thistle be given to horses that have IR | | | | For this test to be accurate the blood that is collected |
| because it has a protective effect on the liver. It also | | | | must be centrifuged to separate the serum within 30 |
| contains certain minerals, such as selenium, which help | | | | minutes to one hour, and then the serum should be |
| some horses cope with the muscle soreness that can | | | | chilled and sent promptly to a lab. If the blood is not |
| occur with IR. I suggest one tablespoon daily of | | | | handled appropriately it will give a falsely low glucose |
| freshly-ground milk thistle seeds. | | | | reading. In many cases the glucose and insulin reading |
| Mineral Deficiencies or Imbalances | | | | may be within the normal range but the ratio will still |
| Many minerals are important for carbohydrate | | | | show IR. The trick is not to wait for your horse's lab |
| metabolism, including but not limited to magnesium, | | | | readings to go outside the normal ranges before |
| chromium, manganese, and zinc. Mineral imbalances | | | | making changes in the way you manage your horse. |
| can also cause relative deficiencies if too much of one | | | | Luckily, performance horses with IR tend to respond |
| mineral interferes with the absorption of another. For | | | | well to dietary changes. The main thing is to get the |
| example, magnesium and calcium use the same | | | | NSC levels down. Most sweet feeds contain 60% |
| pathway for absorption so an excess of calcium can | | | | NSC so it is almost impossible to get the levels low |
| cause a deficiency of magnesium, even if the minimum | | | | enough. Oats are 50% NSC, making it a challenge to |
| requirement for magnesium in the diet is being met. | | | | feed but it can be used in very small amounts if |
| The only way to definitely determine the mineral levels | | | | combined with grass hay plus alfalfa hay to bring the |
| in your horse's diet is to test all of your horse's feed | | | | energy up. A diet of 3 pounds of oats, 3 pounds of |
| and hay. While this can be difficult it is worth the effort | | | | alfalfa and, 12 pounds of grass hay would still have a |
| if your horse might be insulin-resistant. The website will | | | | NSC level of 18%, which is too high. |
| give you the information you need to send in the | | | | A better diet would be 2 pounds of rice bran, 4 |
| correct samples. For horses that are not showing | | | | pounds of alfalfa, and 12 pounds of grass hay, which |
| serious symptoms I prefer to look at the typical levels | | | | offers enough calories for a horse in light work and still |
| of nutrients in regional hay and feed samples; make | | | | has a NSC level of around 14%. This diet also has a |
| sure the diet is balanced for macro minerals like | | | | 3.5% fat content, so it is not likely trigger any digestive |
| calcium, phosphorus, and magnesium; and then use a | | | | upsets. Some feed companies are now recognizing IR |
| food source that contains easily assimilated minerals, | | | | and listing the NSC ratios of their feeds. If you want to |
| like blue-green algae, as a supplement to provide the | | | | simplify your math you can get one of these feeds |
| micro minerals. | | | | and then test just your hay. If you don't buy large |
| Lack of Exercise | | | | amounts of hay you may be able to ask your supplier |
| Lack of exercise can affect the horse in several | | | | to test his loads as they come in and let you know the |
| ways. First, it creates stress in many horses. Second, it | | | | NSC levels of the hay you are buying. If you are not |
| contributes to obesity. Most diets designed for | | | | able to test your hay you can soak it for 30 minutes in |
| performance horses are based on keeping the horse | | | | hot water or one hour in cold to lower the sugar levels. |
| at the correct weight when he is in work. As soon as | | | | This may seem like a lot of work but could make a big |
| the horse goes off work, either because of an injury | | | | difference in your horse's health! |