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For horses · Apr 14, 2021

Most horses are getting the wrong oil for the wrong reasons

Everyday horse diets are already loaded with omega-6 fats, so the oil you add to the feed bucket matters a lot more than most people realise.

Dapple grey horse at a stable yard as golden oil is poured into a feed bucket

By Beryl Shuttleworth, BSc Hons Biochem

Last reviewed: 2026-07-22

Yes, feeding oil to horses is a good idea, and most horses handle it well. A splash of the right oil supports a glossy coat, helps keep inflammation in cheque, and tops up the essential fats that a modern diet often misses. The catch is that most horses already get plenty of omega-6 from their feed, and too much omega-6 relative to omega-3 can tip the balance towards inflammation. That’s why I favour flaxseed oil, it’s rich in omega-3 and does a decent job of raising EPA levels in the blood. Just add it slowly at first to keep the digestive system happy.

ALA from plant oils can’t be converted to useful EPA and DHA in horses

This one does the rounds in equine nutrition circles, and I get why it stuck, in humans, the body is pretty poor at turning the plant-based fatty acid ALA into the longer-chain omega-3s your horse actually needs. So people assume horses are the same. They’re not, at least not entirely.

Here’s what the research actually shows: when you feed horses a plant oil that’s rich in ALA, like flaxseed oil, their circulating levels of EPA do go up, meaningfully [2]. Horses are noticeably better at making that first conversion than humans are. So you are getting real, biologically active omega-3s into your horse, not just feeding something that sits there doing nothing.

Now, there is a genuine limitation, and I won’t gloss over it. That same research shows that flaxseed oil does not raise DHA levels in horses [2]. The final step, turning EPA into DHA, is where horses hit a wall. So the honest picture is: ALA to EPA, yes; ALA to DHA, not reliably.

What that means for you practically is that plant-based oils are a perfectly legitimate way to get more EPA into your horse, and EPA is the fatty acid that plays a direct role in keeping the inflammatory response in cheque [4, 5]. The sweeping claim that plant oils are useless because horses “can’t convert ALA” just doesn’t hold up to scrutiny.

How dietary oils work in your horse’s body

The problem with most modern horse diets comes down to one thing: too much omega-6, not enough omega-3. As vegetable oils high in omega-6 became the norm, the balance tipped, and that matters, because high omega-6:omega-3 ratios are linked to inflammatory and autoimmune problems, while bringing the ratio back into balance actually improves performance markers. I should say, though, that omega-6 isn’t the villain it’s sometimes made out to be. Both fatty acid families do important jobs in the body. The “omega-3 good, omega-6 bad” line is too simple. What the research consistently points to is that the *ratio* is what counts.

Oils like flaxseed and camelina are rich in ALA (alpha-linolenic acid), which is the plant form of omega-3. Horses are reasonably good at converting ALA into EPA (eicosapentaenoic acid), you can measure the rise in circulating EPA after flaxseed oil supplementation. The conversion through to DHA (docosahexaenoic acid), however, is much more limited in horses than it is in humans, so flaxseed oil raises EPA but doesn’t raise DHA by the same amount. Worth knowing if you’re comparing horse nutrition to what you might read about human omega-3 research.

On the inflammation front, the evidence is quite clear. Horses in training given flaxseed oil showed smaller rises in interleukin-1β, basically a marker of inflammation the body produces in response to hard work. A flaxseed oil blend also blunted exercise-related spikes in creatine kinase, which is what goes up when muscles take a battering. Separately, omega-3 supplementation has improved outcomes in horses with respiratory disease and helped support healthy early inflammatory responses.

For skin and coat, a 16-week trial comparing camelina, flaxseed, and canola oils found that all three supported skin and coat health comparably, with no adverse effects on general health markers. Traditional horse keepers got there long before the clinical trials, too, coconut oil was a go-to for making coats shine, and other plant-based preparations were rubbed on for the same reason. That kind of long-standing practical knowledge is worth paying attention to.

One last thing that often surprises people: horses already get around 30% of their resting energy from volatile fatty acids produced in the caecum. Fat metabolism isn’t foreign to the equine system, it’s built in. Dietary oils are simply working with a system that’s already designed to use them.

How to feed oil to your horse without causing digestive upset

Start low and build gradually

The Merck Veterinary Manual recommends starting at 0.1 mL per kg of bodyweight and working up slowly, tip too much in too soon and you risk upsetting the gut. I’ve always said the same thing: give the digestive system time to catch up, and it will.

How much can a horse actually handle?

More than most people realise. Research shows horses can work up to 20% oil in the diet after about ten months of gradual introduction, with fat making up roughly 27% of digestible energy overall. That’s a generous ceiling, but you only reach it safely by taking your time. The slow build isn’t just good advice, it’s what makes high-fat feeding possible in the first place.

This isn’t something you’ll see results from overnight

The skin and coat study comparing camelina, flaxseed, and canola oils ran for 16 weeks. The muscle-support study in young horses in training ran for 60 days. So if you’re feeding oil for coat condition, to help with inflammation, or to support recovery from exercise, be patient, give it at least 8 to 16 weeks before you judge whether it’s working.

How to add it to the feed

Mix the oil directly into the hard feed and stir it through properly. This helps with palatability, keeps the dust down, and, most importantly, spreads the fatty acids evenly through the meal rather than delivering them all at once.

Frequently asked questions

Is it safe to feed oil to horses?

Yes, horses handle oil really well, as long as you introduce it gradually. The Merck Veterinary Manual suggests starting at 0.1 mL per kg of body weight and building up slowly so the digestive system has time to adjust. Research backs this up too: horses can comfortably work up to around 27% of their digestible energy coming from fat, with no ill effects on their general health.

Which oil is best for horses, flaxseed, canola, or camelina?

For skin and coat, a well-designed trial showed that camelina, flaxseed, and canola oils all did a comparable job over 16 weeks. Where they part ways is in their fatty acid make-up. Flaxseed oil has the richest omega-3 content, which makes it my top pick for rebalancing a diet that’s heavy on omega-6, as most modern horse feeds are. Canola is a decent budget option. Sunflower and olive oils are mostly omega-6, so they’re not the right tools for that job.

Can horses convert plant-based omega-3 (ALA) into EPA and DHA?

Partly, yes. When horses are fed flaxseed oil, their circulating EPA levels do go up, so the conversion from ALA to EPA is happening. DHA is a different story, blood levels don’t rise much at all with flaxseed feeding, suggesting that particular conversion is quite limited in horses. Whether ALA has its own benefits beyond what it converts into is still an open question in the research.

Why does the omega-6 to omega-3 ratio in a horse’s diet matter?

When the diet tips too far towards omega-6, it can drive inflammation and is linked to a greater risk of inflammatory and autoimmune conditions. A more balanced ratio helps the body stay on an even keel and keeps energy and nutrients available for performance. The problem is that modern horse feeds, most of which are based on vegetable oils, have quietly shifted towards much higher omega-6 content over time. Topping up with a good omega-3 source like flaxseed or camelina oil is the most practical way to bring things back into balance.

Can feeding oil help horses in training recover from exercise?

There’s promising evidence from a 60-day study in young horses in training. Both flaxseed and rice bran oils helped keep a key inflammation marker, interleukin-1β, from climbing as high as it otherwise would during training. A flaxseed oil blend also appeared to limit the rise in creatine kinase after exercise, which is a sign of muscle stress. It’s not a magic fix, but it’s a meaningful finding for horses in hard work.

Does feeding omega-3 oil to horses cause any vitamin E or oxidative stress problems?

Research in growing horses found no evidence that omega-3 supplementation harmed vitamin E levels or caused oxidative stress. That said, omega-3 fats are polyunsaturated, which means they’re naturally more prone to oxidation than saturated fats. So while the science is reassuring, it’s still sensible to make sure your horse is getting enough vitamin E alongside their oil, especially at higher amounts.

Sources

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