When you think about a horse’s diet and feed program, I’m sure fish oil is not at the top of your list.

Fish oil seems to still be a fairly new concept for many, and is often met with a look of skepticism – horses are herbivores, after all, so meat and fish are not common equine fare.

But it really isn’t all that new. Icelandic horses, a small, hardy breed native to Iceland and descended from Mongolian horses, have been eating fish for a long time, likely since domestication. They didn’t catch the fish themselves, of course, but were provided with barrels of “free-choice” salted fish in their winter pastures when other food and forage became scarce.

Now I don’t think many of us relish the idea of giving our horses a nice salty herring with their evening grain. Thankfully, you can buy fish oil supplements for horses that can be added as a top dress to grain. Fish oil is the fat from fish, and doesn’t contain fish protein.

Understanding EFAs
Essential fatty acids (EFAs) have become all the rage in human diets, and that has spilled over into animal diets as well. Essential fatty acids are “good fats” (polyunsaturated), and are necessary and mandatory for many body functions, including brain function, cellular repair, and immune, cardiovascular and reproductive support. They must come from your diet, as the body cannot produce them on its own. Omegas 3 and 6 are the two families of EFAs.

Omegas over time
Before domestication, horses consumed omegas 3 and 6 in approximately a 1:1 to 4:1 ratio, from their diet of free-choice herbs, forage and occasional grains. Once we began putting horses to work, we started looking for ways to add energy and bloom to them. Riders began to add corn oil to the feed as a common top dress. It is still very common to feed corn oil to horses, particularly in show and race barns. While it certainly works, it throws off the balance of omega-3 to omega-6 significantly.

Omega-6 is the most prevalent omega in today’s complete feeds, due to vegetable oils (most commonly corn oil) and its prevalence in cereal grains (i.e. corn, wheat). Omega-3 is expensive and difficult to add to feeds, given its propensity to become rancid when exposed to the air. Omegas 3 and 6 should essentially be fed in balance with one another. Omega-3 fights inflammation while omega-6 promotes it, so if more omega-6 is being ingested, then the beneficial effects are lost. Both horses and humans are typically omega-3 deficient due to our modern diets. The human balance of omegas should be approximately two to four times omega-6 to 3, but it tends to be 14 to 25 times more omega-6 to 3.

“The point to be made is that the food industry has created fatty acid imbalances through the overuse of less expensive fatty acids and partially hydrogenated oils in manufactured food/feeds that can be harmful to both horses and humans,” writes Dr. Bo Martenson in Good for You, Even Better for Horses! “Some horse owners actually compound the negative effects by adding corn oil to the horse’s diet thinking that it offers a beneficial source of energy.”

Omega -3
Omega-3 is a polyunsaturated fatty acid found in fish, certain plants and nut oils. It provides extra calories in a beneficial and highly useable form. It plays a vital role in cellular repair and formation, brain function, growth and development. It reduces inflammation and improves calcium deposit and bone strength. Omega-3 has been proven to help horses with stomach ulcers, arthritis, allergies, auto-immune diseases, hoof quality, reproduction, joint health, laminitis, respiratory issues and more. It also decreases the risk of colic and pulmonary bleeding.

Omega -6
Omega-6 is another polyunsaturated fatty acid that assists with brain function, growth and development, and is found mainly in plant and grain oils. However, it also promotes inflammation, and can lend to the development of inflammatory diseases if the level of omega-6 greatly overtakes that of omega-3. “Too much omega-6 and too little omega-3 fatty acids has been recognized as a major predisposing cause of the degenerative changes observed in arthritic horses,” writes Dr. Martenson. “In cases of arthritis with cartilage degradation, there is found high concentrations of omega-6 fatty acid derivates creating inflammatory mediators. Two of these mediators, PGE2 and LTB4, are considered the prime culprits in instigating the inflammation process in arthritis.”

That doesn’t mean omega-6 is the “bad guy”. It is still essential. Inflammatory responses have their place and are necessary – you want to see inflammation when your horse injures himself, because it will draw your attention to the injury and aid in the healing process. The problem arises when omega-3 and 6 become so out of balance that the body gets confused and sometimes turns on itself, resulting in issues such as arthritis and auto-immune diseases.

Sources of Omega -3
So why not feed something like flax to your horse as a source of omega-3? This is where things get a little technical. The body best utilizes omega-3 in long-chain eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) form. Omega-3 from flax consists of short-chain alpha-linolenic acids (ALA) that must be converted to the long-chain acids in order to be useful. And too much omega-6 hinders the conversion of ALA to DHA/EPA. This is not the case with fish oil, as no conversion is necessary. Canola and soy oils are better than flax in this respect, but still have a higher percentage of omega-6 than is ideal.

Any natural source of omegas is beneficial to your horse. But if you want the most bang for your buck, fish oil will help provide him with the omega-3s so sorely lacking in most modern feed programs, and in a highly available and useable form.


  1. I have a question, my horse gets flax through the digestive enzymes I feed him is it okay to add the herring oil that I recently bought or will that mess his system up? He is a ten year old thoroughbred and I have had him for two years. He also gets a litre of purina senior plus the cup of digestive enzymes one time per day but he gets his grain twice per day.