Insulin dysregulation (ID) can be incredibly frustrating and difficult to manage, but it doesn’t have to mean a lifetime of frustration. ID is more common in easy-keeping, energy-efficient horses and certain breeds, but no horse is immune: it can affect horses of any age, breed, or body condition.
Obesity is one of the biggest risk factors, but a horse doesn’t have to be overweight to be insulin dysregulated. That’s why regularly assessing body condition and keeping an eye out for regional fat deposits, such as a cresty neck, matters.
The good news? Insulin sensitivity can often be improved with thoughtful, consistent management and regular activity. As always, diagnosed or suspected ID should be managed in partnership with your veterinarian, particularly if your horse has a history of laminitis. But there is plenty you can do as an owner to support better metabolic health day to day. Here you’ll find the 5 most important things you can do to support an insulin-dysregulated horse.
1. Active Lifestyle & Exercise
Movement is one of the most powerful means we have for improving insulin sensitivity, but to understand why exercise is so valuable for an insulin-dysregulated horse, it helps to understand what’s actually going wrong. Insulin resistance is when the body’s tissues are less responsive to insulin, so the pancreas may compensate by producing more insulin to keep blood glucose under control. Persistently or excessively elevated insulin can have serious consequences in susceptible horses and is strongly associated with an increased risk of endocrinopathic laminitis. The concern isn’t simply that a horse has difficulty handling sugar and starch; it is the resulting metabolic dysfunction and, particularly, the potential for prolonged hyperinsulinemia to contribute to laminitis. (Hyperinsulinemia is when insulin levels in the bloodstream are abnormally high.)
This is where exercise becomes such a valuable tool. When muscles contract during exercise, they can increase their uptake of glucose from the bloodstream through mechanisms that don’t rely entirely on insulin. This gives working muscles another way to use circulating glucose and can help improve glucose disposal. With regular training and active lifestyle, exercise can also improve insulin sensitivity, meaning the body can accomplish the same job with a smaller insulin response.
In other words, exercise isn’t just about burning calories or helping an overweight horse lose weight. It’s also about improving how the body handles glucose and responds to insulin. For a sound horse, consistent, progressive movement — from walking and hacking to conditioning and more intensive work — can be an important part of managing insulin dysregulation.
Merits of Muscle Mass
Lean muscle mass is an important part of metabolic health because skeletal muscle is one of the body’s major sites for glucose disposal. The more healthy, active muscle a horse has, the greater its capacity to take up and use glucose from the bloodstream. Building and maintaining lean muscle can give an insulin-dysregulated horse a larger, more efficient “sink” for circulating glucose, helping support better glucose regulation and potentially reducing the amount of insulin needed to manage that glucose load. For the metabolic horse, muscle isn’t just movement tissue; it’s metabolically active tissue that helps the whole system handle glucose more effectively.
Research in horses and ponies has demonstrated improvements in insulin sensitivity with regular exercise, and low-intensity exercise combined with dietary modification may be more effective than dietary restriction alone.
Consistent movement in an active lifestyle is better than occasional hard workouts. Incorporating feeding stations in your paddock can encourage movement, and keeping the water trough, shelter, and food sources spaced apart encourages more walking. And never forget the importance of socializing and friendships. Horses with friends are going to have lower stress levels with movement associated with their social interactions.
Walking, hacking, conditioning, groundwork, and HILLS all have a place, depending on the horse’s fitness and ability. Exercise should be introduced progressively, particularly in previously sedentary horses.
2. Remove Sugar & Starch
For an insulin-dysregulated horse, controlling dietary sugar and starch is another one of the most important pieces of the management puzzle. Low-NSC forage should form the foundation of the diet, because forage is typically the largest component of a horse’s daily intake. Current recommendations commonly aim for forage containing approximately 10% NSC or less on a dry matter basis, although individual horses may respond differently and some management programs may use a threshold closer to 12%. The most appropriate target should be determined according to the individual horse, their insulin response, body condition, and history.
This is why hay analysis is so valuable. You cannot reliably determine the sugar and starch content of hay by looking at it, smelling it, or knowing that it is “timothy,” “orchard,” or another particular forage species. NSC can vary considerably between individual fields, cuttings, growing conditions, and even bales from the same harvest. A laboratory analysis provides actual numbers that can be used to make informed feeding decisions rather than relying on assumptions.
So why are sugar and starch such a concern?
When rapidly digestible carbohydrates are consumed, glucose can become available for absorption relatively quickly. In a healthy horse, the resulting increase in blood glucose and insulin is a normal part of nutrient metabolism. But in an insulin-dysregulated horse, the insulin response may be excessive or prolonged relative to the amount of glucose being handled. Repeatedly exposing these horses to this sort of reaction can therefore contribute to the hyperinsulinemia we are trying to prevent.
Importantly, the problem isn’t that horses need to avoid glucose altogether. Glucose is an essential fuel, and carbohydrates are a normal part of a horse’s diet. The goal is to avoid unnecessarily large and rapid influxes of glucose while providing the horse with an appropriate amount of energy and essential nutrients.
This means looking beyond the feed bucket. Grain, sweet feeds, pelleted feeds containing significant amounts of cereal grains, molasses-based products, and many commercial treats can contribute substantial amounts of sugar and starch. Even small extras can become significant if they’re given repeatedly throughout the day. Choosing low-NSC feeds and treats and eliminating unnecessary concentrates altogether can substantially reduce the overall load.
Pasture deserves particular attention. Fresh grass can contain significant amounts of water-soluble carbohydrates, and its sugar content can fluctuate with plant maturity, weather, season, time of day, and other environmental factors. A horse with ID may therefore consume a surprisingly large carbohydrate load while appearing to be doing nothing more than grazing. For many horses (especially those with ID), unrestricted access to pasture simply isn’t compatible with maintaining healthy insulin regulation. Options such as restricted turnout, a grazing muzzle, a dry lot, or a track system can help control both sugar and calorie intake.
And here’s an important point that often gets lost in conversations about “low sugar” diets: low NSC does not automatically mean low calorie. A horse can consume low-sugar, low-starch hay and still gain weight if they are eating more energy than they require. Conversely, simply restricting calories without paying attention to NSC may leave an insulin-dysregulated horse consuming a carbohydrate load that continues to provoke an undesirable insulin response.
For this reason, carbohydrate management and calorie management need to be considered together. The goal isn’t simply to feed as little as possible or eliminate every gram of sugar and starch. It’s to provide sufficient forage to support healthy gastrointestinal function and minimize hunger while selecting forage and feeds that keep dietary NSC appropriately low and total energy intake appropriate for the individual horse.
For many insulin-dysregulated horses, this means making low-NSC forage the foundation, eliminating unnecessary high-NSC concentrates and treats, carefully managing pasture exposure (if dry lot is unavailable), and regularly reassessing the diet as body condition and metabolic status evolve.
Don’t hesitate to contact us if you have any questions about this!
3. Weight Loss & Weight Management
For an overweight horse, reducing excess body fat can be one of the most effective ways to improve metabolic health. Adipose tissue isn’t simply passive energy storage, it is metabolically active tissue. Fat cells release hormones and other signaling molecules, including adipokines and inflammatory mediators, that can influence appetite, inflammation, and the body’s sensitivity to insulin. Excess adiposity, particularly abnormal regional fat accumulation such as a cresty neck or fat deposits at the back of the ribs (what I like to call a muffin-top), and around the tailhead, is associated with an increased risk of insulin dysregulation.
This means that for an overweight insulin-dysregulated horse, reducing excess fat can improve insulin sensitivity and may reduce the exaggerated insulin responses that put susceptible horses at risk of endocrinopathic laminitis. In many cases, improving body condition is one of the most powerful metabolic interventions available.
However, weight loss should be controlled rather than extreme. Simply restricting food as much as possible isn’t a healthy or sustainable approach. Excessive calorie restriction can result in nutritional deficiencies, excessive hunger and stress (which creates a whole slew of new problems), loss of lean muscle, and other metabolic consequences. Horses still need adequate protein, vitamins, minerals, essential fatty acids, and sufficient forage to support gastrointestinal health.
The goal is therefore to create a moderate, sustainable calorie deficit while maintaining nutritional adequacy. For an overweight horse, this may involve measuring forage rather than feeding free-choice, selecting lower-calorie forage, eliminating unnecessary concentrates and treats, increasing appropriate exercise, and managing pasture access. The specific approach should be based on the individual horse’s current body condition, workload, forage analysis, and nutritional requirements.
Regularly measuring body weight and body condition score makes it possible to determine whether the plan is actually working. A weight tape or body-weight formula won’t provide a perfect measurement, but tracking the trend over time is extremely useful. Combining weight measurements with body condition scoring and, ideally, measurements such as neck circumference can provide a much clearer picture of changes in body composition than visual assessment alone.
It’s also important to remember that not every insulin-dysregulated horse needs to lose weight. Although obesity and regional adiposity are significant risk factors, lean and normal-condition horses can also have ID. Attempting to make an already-lean horse thinner will not solve the underlying problem and can create an entirely different set of nutritional and health concerns.
4. Pasture Management, Dry Lot, or Track?
For some horses, controlling pasture access is one of the most important — and most difficult — parts of managing insulin dysregulation. Grass is forage, after all, so it can be easy to assume that allowing a horse to graze naturally must be healthy. But for an insulin-dysregulated horse, unrestricted access to pasture can provide far more sugar, starch, and calories than they need. If you have access to a dry lot, use it.
Pasture carbohydrates are also notoriously variable. The NSC content of grass can change with plant maturity, species, weather, temperature, sunlight, drought stress, frost, season, and even the time of day. Cool-season grasses, which make up much of the pasture available to horses in many regions, can accumulate significant amounts of water-soluble carbohydrates under certain conditions. A horse can therefore consume a very different carbohydrate load from the same pasture on different days, or even at different times of the same day.
If you don’t have access to a dry lot, when is it safest to turn your horse out?
The sugars in grasses rise gradually throughout the day with exposure to sun, then taper down after sunset. So, the safest hours for turnout are a few hours before dawn, to a few hours after dawn. (Approx. 3am- 10am depending where you live.) Note that stressed grass, esp. from frost, will have higher sugar.
A dry lot provides considerably more control. By removing access to grass and providing measured, low-NSC hay, you can control both carbohydrate and calorie intake much more precisely. But a dry lot doesn’t have to mean standing in a barren pen all day. With appropriate forage provision, slow-feeding systems, companionship, enrichment, shelter, and feed stations to encourage more movement, it can be designed to meet many of a horse’s physical and behavioural needs.
A track system can offer another option, particularly for horses that benefit from increased movement but need their grass intake restricted. By placing forage, water, shelter, and other resources strategically around a track, the system can encourage horses to walk more throughout the day while limiting access to large areas of continuously available grass. The amount of movement and grazing control will depend heavily on the design and the individual horse, however, so a track isn’t automatically metabolically appropriate simply because it’s called a track.
The same principle applies to grazing muzzles. They can substantially reduce grass intake for some horses while allowing continued turnout and social interaction, but fit, tolerance, and actual effectiveness need to be monitored. A muzzle that a horse can easily defeat, or one that creates welfare problems, isn’t a successful management strategy.
Ultimately, the best turnout system is the one that allows you to control the variables that matter. How much forage is the horse consuming? How much NSC is in that forage? How many calories are they receiving? How much are they moving? And how is their body condition and insulin regulation responding?
We don’t want horses to feel punished as that will create more issues. Ideally, we can create an environment where their forage intake, calories, movement, and opportunities for healthy, normal horse behaviour can can all be accommodated. For some horses that may mean a dry lot; for others, a grazing muzzle, restricted turnout, or carefully designed track may provide a healthier compromise.
5. Nutritional & Herbal Support
With the major management pieces are in place, nutrition can be fine-tuned to ensure the horse is receiving everything they need without adding unnecessary calories or NSC. A metabolic diet still needs to be a complete diet. Reducing sugar and starch, restricting calories, and removing concentrates can be very effective strategies, but if those changes aren’t carefully formulated, they can also inadvertently create nutritional deficiencies or imbalances.
This is particularly important during weight loss. When forage intake is restricted, the horse may consume less protein, essential amino acids, vitamins, and minerals along with the reduction in calories. Simply adding a handful of a vitamin-and-mineral supplement isn’t necessarily enough, either; the appropriate amount depends on what the horse is already receiving from forage and other feeds. Forage analysis is therefore an extremely valuable starting point for determining where the diet is adequate and where supplementation is actually needed.
For many insulin-dysregulated horses, a low-NSC ration balancer or appropriately formulated vitamin-and-mineral supplement can be an excellent way to fill nutritional gaps without adding a significant amount of calories, sugar, or starch. Protein quality deserves particular attention as well. When calories are restricted, maintaining adequate protein and essential amino acids helps support lean muscle mass — which, as we’ve already discussed, is itself important for glucose utilization and metabolic health.
Other nutrients may also warrant consideration based on the individual horse’s diet. For example, if your horse has been moved to a dry lot, they are at greater risk of inadequate vitamin E intake. Vitamin E, a powerful antioxidant, rapidly degrades after harvesting hay, thus these horses are unlikely to receive adequate amounts from hay alone. Metabolic dysfunction and obesity are associated with increased oxidative stress which can increase individual requirements of vitamin E, but it’s worth checking bloodwork and working with an advisor or nutritionist to evaluate the current diet and develop a feed management plan.
There are many products marketed specifically for insulin sensitivity, but evidence in horses is often limited, inconsistent, or based on small studies. And ultimately, adding a supplement to support insulin regulation isn’t going to make up for high NSC hay or a lack of exercise. It would be soooo much easier if we could just stick our ID horses on, say, a chromium supplement and watch our worries resolve, but the reality is that these little add-ons are secondary to 1 through 4 on this list.
That doesn’t mean supplements are useless. It means they should have a purpose. There’s no sense spending a ton of money on supplements if you’re not even sure their diet is adequate and balanced.
When herbs or other nutraceuticals are considered, they should be evaluated with a critical eye: What is the proposed mechanism? What evidence do we have in horses? What dose has actually been studied? Is it safe for this individual? And is there a meaningful reason to use it?
Good metabolic nutrition isn’t about finding the perfect supplement. It’s about making sure every part of the diet has a purpose.
We will dive deeper into the roles of nutrients and evaluate the uses of herbs in future posts, but you would be surprised how many horses simply lack a well-balanced, nutrient-adequate diet. That’s the best place to start with dietary support.