askHELTIE HELTIEhorse® What is the difference between IR and EMS in horses?

What is the difference between IR and EMS in horses?

Insulin resistance (IR) and Equine Metabolic Syndrome (EMS) are two related, but different, conditions in horses. Both diseases involve a disturbed metabolism and excess weight. To help your horse properly, it is important to know exactly what is going on.

Insulin resistance

Diseases

31 March '25 • 1 min reading time

What is Insulin Resistance (IR)?

Insulin resistance is a condition in which a horse's cells become less sensitive to the hormone insulin. This means that the body becomes less efficient at absorbing glucose from the blood. Since the glucose is no longer properly removed from the blood, blood sugar levels increase. As a result, the horse has more difficulty maintaining balanced blood sugar levels. The primary cause of insulin resistance is overweight. When a horse receives more feed or a diet higher in sugar than necessary, it can lead to weight gain and eventually IR. A diet containing too much sugar and starch, combined with too little exercise, can contribute to the development of insulin resistance. This can lead to laminitis. Common signs include a thickened crest or fat deposits on either side of the tail. The excess sugars that horses consume do not only come from concentrated feed but also from sugar-rich grass.

What is Equine Metabolic Syndrome (EMS)?

EMS is a complex syndrome characterized by a combination of overweight, insulin resistance, and laminitis. IR is, therefore, a part of EMS. In the Netherlands, approximately 55% of leisure horses are overweight. Due to excess weight, these horses often perform less effectively and may struggle to regulate their body temperature. An overweight horse can become insulin resistant (IR), and obese horses may also develop a disrupted fat metabolism. This happens in horses with EMS, as their entire metabolism and hormone balance are affected by obesity. Horses with EMS are also at a higher risk of developing laminitis. A horse with EMS will have noticeable excess weight, with fat deposits clearly visible, for example, on the neck. The syndrome can result from genetic predisposition or from an overly rich diet with too much sugar and insufficient physical activity. In most cases, it is a combination of these factors. EMS is a serious condition that requires action. The most important aspect is to prevent your horse from becoming overweight or to work towards healthy weight loss. Proper feeding management and sufficient exercise are crucial in this regard.

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Insulin resistance

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In previous blogs, we have indicated what insulin resistance is and that this is often the cause of rubbing in horses and ponies. For horses and ponies with Insulin Resistance, the most important thing is to adjust the ration to a limited intake of sugars. But did you know that salmon oil can also have a positive effect on insulin resistance?

Salmon oil for Insulin Resistance (IR)

In previous blogs, we have indicated what insulin resistance is and that this is often the cause of rubbing in horses and ponies. For horses and ponies with Insulin Resistance, the most important thing is to adjust the ration to a limited intake of sugars. But did you know that salmon oil can also have a positive effect on insulin resistance?. Salmon oil lowers the glucose level in the blood American researchers have discovered that horses fed salmon oil not only have a lower heart rate during exercise, but that the cholesterol and glucose levels in the blood were also lower than in horses that did not receive salmon oil. Because salmon oil has a positive effect on the glucose level, salmon oil is very suitable for horses with Insulin Resistance. Salmon oil reduces inflammation A horse with Insulin Resistance often rubs the mane as a...

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Insulin resistance

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Omega 3 fatty acids are always lumped together under the characteristic "anti-inflammatory". But there are different types of omega 3 fatty acids: ALA, EPA, and DHA. EPA and DHA are the most important for the body. However, these are not found in plant oils such as flaxseed and olive oil. The horse's body still has to convert ALA to EPA and DHA on its own. And in horses with Insulin Resistance (but also summer eczema and overweight), ALA can actually be pro-inflammatory if the body cannot convert them properly. That's why in many cases, it is better to choose directly absorbable EPA and DHA. Read in this blog how that works.

Insulin resistant horse: choose for directly absorbable EPA and DHA omega-3

Omega 3 fatty acids are always lumped together under the characteristic "anti-inflammatory". But there are different types of omega 3 fatty acids: ALA, EPA, and DHA. EPA and DHA are the most important for the body. However, these are not found in plant oils such as flaxseed and olive oil. The horse's body still has to convert ALA to EPA and DHA on its own. And in horses with Insulin Resistance (but also summer eczema and overweight), ALA can actually be pro-inflammatory if the body cannot convert them properly. That's why in many cases, it is better to choose directly absorbable EPA and DHA. Read in this blog how that works.. Omega 3 fatty acids in horses There are three types of omega 3 fatty acids: ALA, EPA, and DHA. Horses get ALA through fresh grass, but it cannot be utilized directly in the horse's body. ALA needs to be converted to EPA and DHA, which is a very inefficient process, but for healthy horses, no problem at all. ALA is also found in plant oils (e.g. flaxseed oil and olive oil). The horse produces EPA and DHA through the conversion of ALA. But it can also be provided through fish oil, salmon oil, or a...

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Horses with insulin resistance (IR) are at greater risk of laminitis than horses with optimally healthy sugar metabolism. A horse with IR, recognizable by a hard crest and fat cushions near the tail, should not graze unlimited on sugar-rich grass. But can you never put such a horse or pony in the pasture again? Or are there still possibilities? Many horses are indeed super happy with pasture turnout...

My horse has insulin resistance (IR) - can he still safely graze?

Horses with insulin resistance (IR) are at greater risk of laminitis than horses with optimally healthy sugar metabolism. A horse with IR, recognizable by a hard crest and fat cushions near the tail, should not graze unlimited on sugar-rich grass. But can you never put such a horse or pony in the pasture again? Or are there still possibilities? Many horses are indeed super happy with pasture turnout.... We as owners like to make our horses happy. But unfortunately, unlimited access to the pasture is not suitable for every horse. Especially draft horses, ponies, and horses that have previously had laminitis are at greater risk of the painful condition of laminitis. Does my horse have IR? A horse that is insulin resistant cannot process sugars from food (such as grass and concentrate) well. This leads to fat storage, infections, and loss of energy. Also, the pancreas becomes overloaded. Prolonged...

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