Horses aren’t designed to digest fat the way humans or dogs are. Their entire digestive system evolved on a trickle of coarse, low-fat forage, not a daily dose of liquid oil. Yet somehow, throwing vegetable oil into a feed bucket has become mainstream advice—for weight gain, for coat shine, or for “energy.”
Horses Can’t Digest Liquid Oils
Unlike us, horses don’t have a gall bladder. That is the organ that our body uses to dump put bile and emulsify large quantities of fat. Horses produce a tiny trickle of bile from the liver, all day long, which is just enough to break down the fatty acids (EFAs) naturally found in grasses and herbs, but not the cup of corn oil or soy oil added to his feed. Keep in mind that we are talking about oils, not about fats fed in a more natural way (ground linseed, chia seeds and ricebran).
Oil Blocks Digestion
Here is the problem when adding oil to your horse’s feed:
- Oil isn’t water-soluble, and neither are digestive enzymes.
- Oil doesn’t get broken apart quick enough, so it starts floating over everything, creating a greasy film that stops enzymes from reaching the starches and proteins they are supposed to break down.
- This results in poor digestion, absorption and undigested food sliding straight into the hindgut.
So when starch, protein and the oil that wasn’t broken apart end up in the hindgut, you get a microbial meltdown—colic, laminitis, SIBO, leaky gut, and chronic inflammation.
What About Linseed Oil or Coconut Oil?
Still oils. Still a problem.
Even cold-pressed linseed oil can overwhelm the equine digestive system if fed in liquid form. It may not be as toxic as corn or soy oil, but it still floats, blocks, and bypasses digestion the same way.
Wait—Isn’t Fat an Important Nutrient?
Yes—but here’s the kicker: it matters how it’s delivered.
Horses do need some fat, specifically omega-3 fatty acids, especially when they’re not on fresh pasture. But the safest, most digestible sources are whole food-based and come with fiber, protein, and nutrients in a natural matrix that the horse’s gut can handle.
The Safe Fats:
- Micronized linseed (aka ground flax) – The gold standard. High in omega-3, highly digestible, and anti-inflammatory.
- Chia seed – Another excellent omega-3 source with gut-soothing properties.
- Stabilized rice bran – Adds calories and natural fat without tipping the system into oil overload.
- Hemp seed (optional) – A decent secondary option, though higher in omega-6.
These are fats, not oils. And they’re part of the forage-based and evolutionary-appropriate diet for the horse.
Signs Your Horse Might Need More (Good) Fat
Here’s where we can be practical. Some horses do benefit from fat supplementation, especially if:
- They’re on hay-only diets
- They have dry skin, dull coat, or dandruff
- Their joints seem stiff or creaky
- They’re recovering from illness or weight loss
But the solution isn’t oil. It’s a high-quality, whole food fat source like micronized linseed, added gradually and in amounts the horse can actually digest and use.
Further Reading & Product Picks:
- Best Omega-3 Supplements for Horses
- Micronized Linseed vs. Linseed Oil: What’s the Difference?
- How to Feed the Hard Keeper Horse Without Starch or Oil
Feeding liquid oil to horses is outdated advice rooted in convenience, not biology. It’s time we stop accepting it just because the feed industry or a well-meaning vet said so. Horses evolved on forage and fiber—not vegetable oil.
So, if you’re reaching for the bottle of canola, corn, or soy oil… put it back.
Feed smarter. Go with natural fat sources your horse can actually digest, and skip the grease slick that’s doing more harm than good.