Scientific and Equine Consultant

How and why to feed oil to horses

Dr David Marlin

In simple terms, oils and fats are compounds high in energy that do not dissolve in water. Oils and fats are the same, expect oils describe “fats” that are liquid at room temperature whilst fats are solid at room temperature. The horses’ normal diet does not naturally contain high amounts of oil or fat. For example, most forages only contain 2-3% of their dry weight as fat and most grains/cereals contain 2-5% fat. Despite this, it’s possible to feed horses relatively high amounts of fat (3-4 times their normal intake in common feeds); although not as high as humans who can consume diets which may be over 75% fat!

There are significant advantages to feeding oil to horses. Oil is a safer source of energy than cereals high in starch and is less likely to cause hindgut disturbance. Horses that are in hard work, or who have poor appetite, compromised digestion or who are poor doers may also struggle to consume or get the benefit from large cereal based feeds but can be managed adequately on a high oil diet. This is because the digestibility of oils are higher than that of cereals; in simple terms the horses digestive system can extract the energy from oils more easily than it can from cereals. Oil is also beneficial for horses prone to laminitis, tying-up, colic, Sweet-Itch and other skin conditions. There is also a significant amount of scientific work showing that particular types of oil are beneficial for joint problems. However, it’s not quite as simple as going to the supermarket and buying a large bottle of the cheapest cooking oil. Not all oils offer the same health advantages. And even for the right type of oil you need to be providing the right amount of Vitamin E (1 IU Vitamin E per ml of oil).

Oils such as linseed, sunflower, corn and soya contain a lot of different fatty acid-rich substances called triglycerides. Triglycerides themselves are made up of different types of fatty acids, including the Omega-6 or Omega-3’s. These are often referred to as poly-unsaturated fatty acids (PUFA’s). Omega-3 and Omega-6 cannot be made by the horse and must be obtained from the diet. Modern horse diets are generally high in Omega-6 fatty acids, mostly derived from cereal grains and pulses, or from corn, soya and rapeseed (vegetable) oils. In contrast, the diet is often relatively low in Omega-3 fatty acids.

There are two very important Omega-3 fatty acids, eicosapentaenoic acid, often abbreviated to EPA and docosahexaenoic or DHA. EPA and DHA are the building blocks for hormones that control immune function, blood clotting, and cell growth as well as components of cell membranes and can also influence skin and coat condition. In people our diet has tended to increase in Omega-6’s and decrease in Omega 3’s. This dietary imbalance has been one factor linked to the rise of such diseases as asthma, coronary heart disease, many forms of cancer, autoimmunity and neurodegenerative diseases, all of which are believed to stem from inflammation in the body. The imbalance between Omega-3 and Omega-6 fatty acids has also been proposed to contribute to obesity, depression, dyslexia, hyperactivity and even a tendency toward violence. For these reasons, a diet high in Omega-3 and low in Omega-6’s is seen as highly beneficial.

The potential beneficial effects of Omega-3 fatty acids arise through their ability to alter the Omega-3: Omega-6 ratio in the blood and body tissues, in particular the cell membranes. This in turn modifies the response of many different cells to various inflammatory stimuli, such as occur due to injury, allergens and infectious agents (bacteria, viruses and fungi). Omega-3 fatty acids offer therapeutic potential in certain chronic inflammatory skin conditions, as they can reduce the production of certain prostaglandins; substances that promote inflammation. Of the common sources of oil fed to horses today, linseed is the highest in Omega 3 and lowest in Omega 6 and so has the greatest anti-inflammatory potential.

Within joints, damage to the cartilage leads to inflammation which in turn further damages the cartilage leading to an ongoing cycle. In humans the inflammation is usually controlled with drugs known as NSAID’s (non-steroidal anti-inflammatory drugs; e.g. ibuprofen); in horses the equivalent would be “Bute” (phenylbutazone). In human medicine there has been an increasing amount of work showing that consumption of Omega-3 fatty acids over several months by patients with arthritis and osteoarthritis can reduce the need for anti-inflammatory drugs [1]. There is also a study which showed that Omega-3 fatty acids can reduce inflammation in cells from horse joints [2].

In summary, if your horse loses condition, is prone to skin conditions including Sweet-Itch, prone to tying-up, laminitis, colic or joint problems then introducing oil to the diet whilst cutting back cereals is highly beneficial. As with any diet change in horses, remember to gradually introduce the oil based feed over a period of 1-2 weeks whilst at the same time gradually reducing the amount of cereal being fed.


1 Lopez HL. Nutritional interventions to prevent and treat osteoarthritis. Part I: focus on fatty acids and macronutrients. PM R. 2012 May;4(5 Suppl):S145-54.

2 Munsterman AS, Bertone AL, Zachos TA, Weisbrode SE. Effects of the omega-3 fatty acid, alpha-linolenic acid, on lipopolysaccharide-challenged synovial explants from horses. Am J Vet Res. 2005 Sep;66(9):1503-8.

oil for horses

Date: July 14, 2015