Is this just yet another fad?
The purported benefit of omega-3 fatty acids has been touted for years, long enough that we have both some research as well as anecdotal evidence about what they can and can not accomplish (for a refresher on what they are and their role in human health and nutrition check out the CDC website on this topic: https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/ )
As for equine health benefits, research shows that supplementing the equine diet with PUFAs ("PolyUnsaturatedFatty Acids") can help reduce the symptoms of equine asthma. Other research found that supplementation with PUFAs may be useful in the prevention and treatment of osteoarthritits, and in supporting skin health and coat color. Anecdotal evidence has it that a high amount of freshly ground flax seed, if started before the onset of and fed throughout insect season, can prevent clinical symptoms of culicoides hypersensitivity ("sweet itch"). There also is research showing that PUFAs do not prevent gastric ulcers.
To summarize what we know about the benefits of PUFAs:
| no effect |
| likely |
| possibly |
| yes |
| anecdotal evidence |
Now, if you decide to add some PUFAs to your horse's diet, there is a plethora of supplements available, most of which claim to cure just about any condition from scratches to Cushing's (which should immediately raise suspicions as to the validity of their claims). Or you could go straight to cold-pressed flaxseed or camelina oil, which are a) cheaper, b) plant-based (as opposed to fish oil, which is not a particularly sustainable product, given the state of our oceans and fisheries).
Most equine-specific products advise to feed 30 ml (1 fl.oz.) twice-daily, although the studies I could find vary from 1 ounce to 6 ounces per day, so I would argue that there really isn't any hard data out there to go by. The amount of ground flaxseed to be fed to prevent sweet itch is one pound per day, but this is anecdotal evidence only, reported by colleagues who have seen good success with this. Flaxseed can be bought in bulk online (search for "wholesale nuts and seeds", and a number of distributors will come up). It has to be ground fresh daily, or ground and then stored in the fridge or freezer, as unstabilized ground flaxseed is, well, not stable. The fats it contains, the ones we are looking for, will deteriorate quickly unless kept cool. The same goes for oils containing the long-chain fatty acids (the longer the chain the more sensitive the molecule is to breaking down).