Do Omega-3 Supplements Help Insulin Resistance in Horses?

Do Omega-3 Supplements Help Insulin Resistance in Horses?

By Dr Duncan Houston

Omega-3 supplements are popular in horses for skin, coat, allergy support, inflammation, and general wellness.

But when it comes to insulin resistance, equine metabolic syndrome, and laminitis prevention, the answer is more complicated. Omega-3 fatty acids may have some useful metabolic and anti-inflammatory effects, but they are not a replacement for the things that actually control EMS: low-NSC forage, calorie control, pasture restriction, weight management, exercise when sound, hoof care, and veterinary monitoring.

The risk is not that omega-3s are useless. The risk is treating them like the main solution while the horse is still overweight, cresty, eating high-sugar pasture, or becoming footsore.

Quick Answer

Omega-3 supplements may support insulin regulation and inflammation control in some insulin-resistant or EMS horses, but the evidence is still limited and not strong enough to treat them as a primary therapy. A 2013 study found no clear overall treatment effect from marine or flax omega-3 supplementation, although insulin-resistant mares showed a trend toward improved insulin sensitivity. A later pilot study using DHA-rich microalgae in EMS horses suggested possible metabolic and inflammatory benefits, but larger studies are still needed. (ScienceDirect)

For horses with EMS or laminitis risk, the proven management priorities remain low-NSC forage, restricted calories, reduced or eliminated pasture access, weight loss if overweight, exercise only when sound, and veterinary testing of insulin status. (Center for Equine Health)

What Are Omega-3 Fatty Acids?

Omega-3 fatty acids are fats involved in cell membrane function, inflammatory signalling, immune function, skin health, and general metabolism.

The main types discussed in horse nutrition are:

• ALA, found in plant sources such as flaxseed and chia

• EPA, found in marine sources such as fish oil and some algae-based products

• DHA, found in marine and algae-based products

Flax provides ALA, which the body must convert into longer-chain omega-3s such as EPA and DHA. Marine and algae products provide EPA or DHA more directly. That does not automatically make one source “best” for every horse, but it does matter when interpreting research.

The practical point is this: not all omega-3 products are the same, and a scoop of flaxseed is not identical to a DHA-rich algae supplement.

What Is Insulin Dysregulation in Horses?

Many owners say “insulin resistance,” but in horses the broader and more accurate term is often insulin dysregulation.

Insulin dysregulation can include an exaggerated insulin response after eating sugar or starch, persistently high insulin, reduced insulin sensitivity, or abnormal insulin clearance. Horses with insulin dysregulation may not have high blood glucose like a diabetic person. Many maintain normal glucose but produce too much insulin to do it.

That matters because high insulin is strongly linked with endocrinopathic laminitis.

Equine metabolic syndrome, or EMS, is associated with inappropriate blood insulin levels, increased fat deposition, reduced ability to lose weight, and high laminitis risk. It commonly affects “thrifty” horses such as ponies, donkeys, Arabians, and mustangs, but any horse can be affected. (Center for Equine Health)

Typical EMS warning signs include:

• Cresty neck

• Fat pads around the tailhead, shoulders, sheath, mammary area, or ribs

• Easy weight gain

• Difficulty losing weight

• Recurrent foot soreness

• Laminitis history

• Hoof rings suggesting previous laminitis

• Strong reaction to pasture or high-carbohydrate feed

The horse that worries me most is not always the obviously obese one. It is the horse with a firm crest, subtle foot soreness after grass, and an owner saying, “He lives on nothing.” That horse is often metabolically louder than people realise.

Why Insulin Matters for Laminitis

Laminitis is not just a hoof problem. In many modern cases, it is an endocrine and metabolic problem showing up in the feet.

Merck Veterinary Manual describes endocrine dysfunction as probably the most common underlying cause of laminitis in horses today, with hyperinsulinaemia considered the predisposing condition. EMS and PPID are the major disease processes in this category. (Merck Veterinary Manual)

That is why omega-3s cannot be the main answer.

If a horse has insulin dysregulation, the first priority is reducing the insulin triggers. That usually means controlling non-structural carbohydrates, calories, pasture access, and body condition.

A supplement may support the plan. It cannot replace the plan.

What Does the Research Say About Omega-3s and Insulin Sensitivity?

The research is interesting, but not definitive.

A 2013 Journal of Equine Veterinary Science study examined omega-3 supplementation in 21 mares. Horses were assigned to marine omega-3, flax omega-3, or control groups for 90 days. The supplemented groups received 38 g of omega-3 fatty acids per day from either a fish and algae source or a flaxseed source. The study used frequent sampling intravenous glucose tolerance testing to assess glucose and insulin dynamics. (ScienceDirect)

The results were mixed. Across all horses, the study did not detect a clear treatment effect on insulin sensitivity from fatty acid supplementation. However, in mares classified as insulin-resistant, the marine and flax groups showed a trend toward increased insulin sensitivity compared with controls. The authors concluded that further investigation in a larger group of insulin-resistant horses would be useful. (ScienceDirect)

There was also a major confounder: horses lost weight and body condition during the study period. Weight loss itself can improve insulin sensitivity, so it is difficult to credit omega-3 supplementation alone.

That is the kind of nuance supplement advertising tends to accidentally misplace.

What About DHA-Rich Microalgae?

A later pilot study looked at DHA-rich microalgae in horses with EMS.

In that study, 10 horses with EMS were either fed DHA-rich microalgae providing 16 g of DHA per horse per day for 46 days or served as controls. The treated horses had increased circulating DHA, lower serum triglycerides after supplementation, and a trend toward reduced inflammatory signalling. Interestingly, control horses had an increased insulin response to an oral sugar test after 46 days, while treated horses did not. The authors concluded that DHA-rich microalgae altered circulating fatty acids, modulated metabolic parameters, and may reduce inflammation in horses with EMS. (University of Kentucky)

That is promising, but it is still a pilot study.

It does not prove that omega-3s prevent laminitis. It does not prove they reverse EMS. It does not mean every metabolic horse should be put on a random omega-3 supplement. It means DHA-rich omega-3 supplementation may be a useful add-on worth further research.

Useful? Possibly.

Curative? No.

Should You Use Omega-3s for an Insulin-Resistant Horse?

Possibly, but only as part of a broader plan.

Omega-3 supplementation may be reasonable if your horse:

• Has EMS or insulin dysregulation and the core diet is already controlled

• Has skin allergy or inflammatory skin disease

• Has poor omega-3 intake because there is little or no pasture

• Is on a hay-based diet with limited fresh grass

• Needs support for general inflammatory balance

• Is not receiving unnecessary calories from the omega-3 source

• Has a vet or nutritionist involved in the full ration

Omega-3s should not be your first move if the horse is still eating lush pasture, grain, sweet feed, molasses treats, untested hay, or too many calories.

In practice, the order should be:

1. Diagnose the metabolic problem.

2. Control the forage and pasture.

3. Manage weight and hoof risk.

4. Add supportive nutrients where they make sense.

Not the other way around.

Marine, Algae, or Flax: Which Is Better?

There is no perfect answer for every horse.

Flaxseed

Flaxseed provides ALA, fibre, and fat. It can be useful for skin and coat, and it is commonly used in horse diets.

Potential advantages:

• Easy to source

• Often palatable

• Provides fat and fibre

• Usually less expensive than marine sources

Potential limitations:

• ALA must be converted to EPA and DHA

• Adds calories

• Ground flax needs proper storage

• Not a direct match for DHA-focused studies

Fish Oil

Fish oil provides preformed EPA and DHA.

Potential advantages:

• Direct EPA and DHA source

• More similar to some research models in other species

Potential limitations:

• Palatability can be poor

• Quality varies

• Can oxidise if stored badly

• May smell or affect feed acceptance

Algae-Based DHA

Algae products can provide DHA without using fish oil.

Potential advantages:

• Direct DHA source

• More relevant to the 2019 EMS pilot study

• Often more palatable than fish oil

Potential limitations:

• Can be expensive

• Product quality and DHA dose vary

• Research is still limited

The best choice depends on the horse, the reason for supplementing, the calorie budget, the product quality, and whether you are targeting general omega-3 support or a specific DHA intake.

Risk Framework: How Worried Should You Be?

Low Risk

This is lower risk if your horse:

• Has ideal body condition

• Has no cresty neck

• Has no laminitis history

• Has normal insulin testing

• Maintains weight easily without becoming fat

• Has controlled pasture access

• Is sound and exercising regularly

• Is receiving omega-3s only as general support

This horse may not need omega-3s for insulin reasons, although they may still be useful for skin, coat, or inflammatory support.

Moderate Risk

This is more concerning if your horse:

• Is an easy keeper

• Has a mild crest

• Has fat pads

• Gains weight on pasture

• Has not had insulin testing

• Is eating untested hay

• Is on restricted pasture but still overweight

• Has occasional mild foot soreness

This horse needs diet review, forage testing, weight control, and likely insulin testing before supplements become the focus.

High Risk

This is high risk if your horse:

• Has confirmed insulin dysregulation

• Has EMS

• Has PPID with high insulin

• Has a firm cresty neck

• Is overweight or obese

• Has had laminitis before

• Becomes footsore after pasture

• Has strong digital pulses or hoof rings

• Is still eating pasture, grain, molasses, or high-NSC hay

This horse needs a veterinary-guided EMS plan. Omega-3s may be considered later, but the core management comes first.

Critical

This is urgent if your horse:

• Is suddenly lame

• Is reluctant to walk

• Rocks back onto the hindlimbs

• Has heat in the hooves

• Has strong or bounding digital pulses

• Lies down more than normal

• Refuses to turn

• Is showing severe pain

• Stops eating while obese or metabolically risky

• Has known EMS or PPID and new foot soreness

This is not a supplement question. This is a laminitis concern and needs veterinary attention.

When Is This an Emergency?

Call your vet urgently if your horse has signs of laminitis.

Red flags include:

• Pottery gait

• Reluctance to walk

• Reluctance to turn

• Heat in the hooves

• Strong digital pulses

• Rocked-back stance

• Repeated lying down

• Refusing to pick up a foot because the others hurt

• Sudden lameness after pasture access

• Known EMS or PPID with any new foot soreness

Merck describes laminitis as one of the most important and catastrophic diseases in horses, with potential outcomes ranging from temporary loss of use to life-threatening disease. The hallmark clinical sign is severe lameness with bounding digital pulses. (Merck Veterinary Manual)

Do not exercise a horse with active laminitis.

Do not turn them out to “loosen up.”

Do not wait to see whether a metabolic horse walks it off.

What Else Can Look Like Insulin Resistance?

A horse can look cresty, stiff, overweight, or dull for several reasons.

Important rule-outs include:

• EMS

• PPID

• Insulin dysregulation

• Overfeeding calories

• High-NSC pasture or hay

• Lack of exercise

• Chronic pain limiting movement

• Arthritis

• Laminitis

• Hoof imbalance

• Poor saddle fit

• Pregnancy

• Regional fat deposition without confirmed EMS

• Medication effects

• Inaccurate body condition scoring

• Hidden treats or multiple people feeding

Merck notes that obesity and a cresty neck are not enough to diagnose EMS, and absence of obesity does not exclude insulin dysregulation. Diagnostic testing should focus on documenting insulin dysregulation. (Merck Veterinary Manual)

That is why blood testing matters. Looking at the horse helps. Testing tells you more.

What Should You Do Next?

1. Do Not Start With Supplements

If your horse is cresty, overweight, laminitis-prone, or footsore, start with diagnosis and diet.

Ask your vet about:

• Resting insulin

• Resting glucose

• Oral sugar test

• Oral glucose test

• ACTH testing if PPID is possible

• Hoof radiographs if laminitis is suspected

• Body condition and cresty neck scoring

A supplement is only useful if the main problem is being managed.

2. Test the Hay

For EMS horses, hay analysis is one of the most important steps.

UC Davis recommends that hay for EMS horses ideally contain less than 10% NSC on a dry matter basis. It also notes that hay type alone is not reliable, because grass hay and alfalfa can both vary in carbohydrate content. (Center for Equine Health)

If hay cannot be tested, soaking may reduce some water-soluble carbohydrates, but the reduction is variable and cannot reliably turn unsuitable hay into safe low-NSC forage. (Center for Equine Health)

The test beats the guess.

3. Restrict Pasture if Needed

Pasture can be the biggest insulin trigger in many horses.

For EMS horses, UC Davis recommends NSC restriction, calorie restriction, and reduced or eliminated pasture access. Exercise may be added depending on the horse’s physical condition and soundness. (Center for Equine Health)

For high-risk horses, options include:

• Dry lot turnout

• Track system

• Grazing muzzle

• Strip grazing

• Very limited supervised turnout

• No pasture during high-risk seasons

• Tested low-NSC hay instead of grass

If the horse has active laminitis, pasture should be removed unless your vet gives specific instructions otherwise.

4. Weigh Forage and Manage Calories

For overweight EMS horses, UC Davis recommends initially feeding around 1.5% of ideal body weight in forage per day, with possible reduction to 1.25% after 30 days if necessary. Sudden severe restriction should be avoided because it can worsen metabolic problems. (Center for Equine Health)

Do not feed by flakes.

Do not starve the horse.

Do not assume a round horse is getting “hardly anything” unless the hay has actually been weighed.

5. Add Exercise Only When Safe

Exercise can improve insulin sensitivity and weight loss, but only when the horse is sound.

UC Davis states that controlled and stable laminitis cases may benefit from walking if approved by a veterinarian, but exercise is not recommended for horses with active laminitis. (Center for Equine Health)

If the horse is footsore, the feet come first.

6. Consider Omega-3s as an Add-On

Once the main EMS plan is in place, omega-3 supplementation may be worth considering.

A sensible approach is:

• Choose a reputable product with clear omega-3 content

• Know whether it provides ALA, EPA, DHA, or a combination

• Avoid products loaded with sugar, molasses, or unnecessary calories

• Introduce gradually

• Track body weight and body condition

• Recheck insulin as your vet recommends

• Do not use omega-3s as an excuse to relax pasture or hay control

For a horse with EMS, even “healthy fat” still adds calories. That matters in a weight-loss plan.

7. Monitor the Horse, Not Just the Bloodwork

Track:

• Body condition score

• Neck crest

• Weight tape or scale weight

• Digital pulses

• Hoof heat

• Foot comfort

• Exercise tolerance

• Pasture exposure

• Hay intake

• Insulin testing results

• Any laminitis signs

A horse can look better before the bloodwork is ideal, or have worrying insulin before obvious lameness appears. Use both clinical signs and lab results.

Common Mistakes Owners Make

Treating Omega-3s Like a Cure

Omega-3s may support metabolic management, but they do not cure EMS.

Ignoring Pasture

A horse can receive an excellent omega-3 supplement and still be at high laminitis risk if pasture intake is uncontrolled.

Feeding High-Calorie Fat to an Overweight Horse

Omega-3 supplements contain fat, and fat contains calories. This matters in obese horses.

Using Flax and Assuming It Is the Same as DHA

Flax provides ALA. DHA-rich algae provides DHA. They are both omega-3 sources, but they are not identical.

Skipping Insulin Testing

A cresty neck and obesity suggest risk, but testing helps confirm the problem and guide the plan.

Exercising a Footsore Horse

Exercise helps EMS only when the horse is sound enough to move safely. Active laminitis needs veterinary care and restricted movement.

Trusting Supplement Marketing Over Forage Analysis

If the hay is too high in NSC, no omega-3 product will magically make the diet safe.

How To Manage Insulin Resistance Long Term

Long-term EMS management is built on boring consistency.

Focus on:

• Testing insulin when risk signs are present

• Testing ACTH in older horses or PPID suspects

• Feeding tested low-NSC hay

• Restricting or eliminating pasture when needed

• Weighing forage

• Maintaining ideal body condition

• Monitoring the cresty neck

• Avoiding grain, sweet feed, molasses, and sugary treats

• Using a low-calorie ration balancer if minerals are needed

• Exercising only when sound

• Keeping regular farrier care

• Checking digital pulses in high-risk horses

• Rechecking bloodwork as advised by your vet

• Using supplements only when they fit the full plan

Merck states that diet is the most important element in EMS management, and that dietary adjustment is sufficient to manage most cases. It also notes that hoof care by a skilled farrier is essential in EMS cases, even without obvious acute laminitis. (Merck Veterinary Manual)

That is the hierarchy.

Diet, weight, feet, movement, monitoring.

Then supplements.

Will My Horse Be Okay?

Many horses with EMS or insulin dysregulation do well when the condition is recognised early and managed properly.

The prognosis is better when the horse is not actively laminitic, body condition can be improved, pasture can be controlled, hay can be tested, and insulin is monitored over time. UC Davis notes that many horses respond well to diet and exercise management, but there is no simple cure for EMS and long-term care requires diligence and veterinary support. (Center for Equine Health)

Omega-3s may be helpful for some horses as part of that system.

But if the horse is already footsore, has strong digital pulses, or has active laminitis, the priority is urgent veterinary care, not supplement selection.

FAQs

Can omega-3 supplements reverse insulin resistance in horses?

No. Omega-3 supplements should not be expected to reverse insulin resistance on their own. Research suggests possible supportive effects in some insulin-resistant or EMS horses, but diet, weight control, pasture restriction, exercise when sound, and veterinary monitoring remain the main treatments. (ScienceDirect)

Is flaxseed good for horses with EMS?

Flaxseed can be useful for some horses as an omega-3 source, but it still adds calories. For EMS horses, it should fit within a controlled diet and should not replace low-NSC hay, pasture restriction, or insulin monitoring.

Is fish oil better than flaxseed for insulin resistance?

Fish oil provides preformed EPA and DHA, while flaxseed provides ALA. The 2013 study tested both marine and flax sources and found no clear overall treatment effect, although insulin-resistant mares showed a trend toward improved insulin sensitivity in both supplemented groups. (ScienceDirect)

Should I give omega-3s to a laminitic horse?

Do not focus on omega-3s during active laminitis. Call your vet, remove dietary triggers, restrict movement as advised, provide hoof support, and manage pain. Omega-3s may be discussed later as part of a long-term plan, but they are not emergency laminitis treatment.

What is the best diet for insulin-resistant horses?

The best diet is usually tested low-NSC forage, controlled calories, restricted or eliminated pasture, clean water, salt, and a low-calorie ration balancer if needed. UC Davis recommends hay below 10% NSC on a dry matter basis for horses with EMS. (Center for Equine Health)

Final Thoughts

Omega-3 fatty acids are interesting, and they may have a place in managing some horses with insulin dysregulation or EMS.

But they are not the foundation.

The foundation is still diagnosis, forage testing, calorie control, pasture restriction, weight management, hoof care, and exercise only when the horse is sound. Omega-3s may support the system, especially in horses with limited pasture, inflammatory concerns, or carefully managed EMS, but they should never become the shiny supplement that distracts from the boring work that actually prevents laminitis.

Feed the horse in front of you.

Test the insulin. Test the hay. Watch the feet. Control the grass.

Then decide whether omega-3s add value.

That is smart metabolic management, not supplement roulette.

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If you are unsure whether your horse’s cresty neck, weight gain, insulin results, pasture sensitivity, or foot soreness could be linked to EMS, ASK A VET™ can help you work through the warning signs and decide whether diet changes, testing, or urgent veterinary care are needed.