Sweet Itch… Flaxseed Can Help

One such nutritional alternative with promise is omega-3 fatty acid. Supplementing diets with omega-3s has long been associated with general improvements in skin and coat health in horses. As early as 1966, the scientific literature was reporting an improvement in skin and coat health of horses on diets high in omega-3 fat. While the mechanism of action remains somewhat elusive, it has been proposed that this effect may be associated with the preferential incorporation of omega-3 fats into cell membranes, improving their fluidity and deformability. The other action of omega-3 fats is that they are metabolized to non-inflammatory metabolites including prostaglandins of the 1 and 3 series, unlike the more plentiful omega-6 fatty acids that are metabolized to pro-inflammatory prostaglandin E2. This general shift away from a pro-inflammatory state in horses consuming diets high in omega-3 fat should afford some protection for horses against inflammatory conditions such as that seen in sweet itch.

And in fact, this hypothesis was tested in a study at the Equine Research Centre (University of Guelph) in horses with sweet itch. Horses’ diets were supplemented with ground flax meal (500 grams per day) for 42 days; on days 0, 21, and 42 they were injected subcutaneously with Culicoides extract, saline (negative control), and histamine (positive control). The flaxseed strongly inhibited the allergic skin reaction to the Culicoides injection. 

In this study, flaxseed also reduced the concentration of long-chain saturated fatty acids in the hair. As hair is composed mainly of protein and minerals, any changes in fatty acids must reflect changes in secretions that come from the skin and are deposited into the hair. These secretions form a waterproof coating that supports many bacteria (called “dermal microflora”), and some skin bacteria are known to metabolize compounds (trans-urocanic acid and histidine) that are involved in immune function. By altering the fatty acids of the skin secretions, it is possible that flaxseed altered the ability of bacteria to metabolize these compounds, thus reducing the immune response to Culicoides injection. Flaxseed was also shown to be safe in horses when fed at 500 grams/day, as there were no significant changes in any blood biochemistry or hematology values.