Omega fatty acids are becoming a topic of interest for health benefits in horses, for not only skin and hooves, but mental, digestive, reproductive, pulmonary and joint health too.
While there are several omega fatty acids, only two are of any real concern, omega-3 and omega-6. In the body, omega-3 is in charge of repairing cellular walls and maintaining a fluid and efficient waste-nutrient transfer. It's also critical for brain function, and is instrumental in cleaning up after an injury has healed, acting as a potent anti-inflammatory. Omega-6, on the other hand, is in charge of causing inflammation and immune system reactions, which is necessary to stabilize injuries and fight off infections.
The two operate in a yin-yang fashion, so the quantity of omega -3 and omega-6 is less important than the balance between the two. The correct balance has not been scientifically established for horses; for humans a healthy range is between 1:1 and 5:1 (omega-6 listed first). Because grass and hay (providers of omega-3) and small wild grains (providers of omega-6) are the horse's evolutionary diet, common sense would lead us to believe that a health equine ratio is similar, probably 1:1.
Because grains are a rich source of omega-6, our modern method of feeding horses has likely skewed their omega profile quite significantly. This is certainly true for our own diets, now estimated to be 17:1 to 30:1. This omega-6 overload has been indicated as a culprit in many human health concerns, including heart disease, joint pain, and brain malfunction; now universities are now increasingly studying whether the same is true in equine medicine.
The theory is that horses react to too many omega-6s by developing brain issues (extreme spookiness, unmanageability, anxiety, cribbing), joint health problems (premature arthritis, injuries that fail to heal 100%) and fertility concerns (weak or insufficient sperm, a reliance on hormones for mares), among others. Some early studies are very promising, and more are in the works now.
To "mind the omegas" takes just a few easy steps. First, increase forage and decrease concentrates as much as possible while maintaining a healthy weight. For your concentrate, choose a quality complete feed that promises an improved omega balance. It will still be weighted toward omega-6, but every little bit helps. Finish balancing this concentrate with an omega-3 supplement, such as fish oil made specifically for horses (full spectrum including EPA for joints and DHA for brain and fertility) or flax seed (contains ALA, some of which your horse can translate into EPA and DHA). Finally, stop feeding supplemental vegetable and corn oils, rice bran and sunflower seeds. Virtually all have a profile that is dramatically weighted toward omega-6, only canola at 2:1 is nearly neutral.