Flavonoids are a diverse group of plant-based antioxidant compounds found in fruits, vegetables, herbs, and some forages. They include quercetin, rutin, hesperidin, and catechins, among hundreds of others. In horses, flavonoids have gained interest for their potential anti-inflammatory, antioxidant, and vascular-supportive properties. Quercetin in particular has been studied for its ability to modulate allergic responses and support respiratory health in horses with equine asthma (heaves). Rutin and hesperidin may support capillary strength and reduce exercise-induced oxidative stress.
There is no established requirement for flavonoids in horses. The best way to provide a natural range of flavonoids is through dietary variety — mixed-species pasture, different hay types, and occasional fruit or vegetable treats like apples, blueberries, carrots, and fresh herbs. If you are interested in targeted flavonoid supplementation for a horse with respiratory issues or chronic inflammation, discuss specific products and dosing with your veterinarian.
Flavonoids are not essential nutrients, so there is no deficiency syndrome. Horses have evolved eating flavonoid-rich plants, and a varied forage diet naturally provides a wide range of these compounds. Horses on monotonous diets (single hay type, no pasture variety) may receive fewer flavonoids, but this does not cause recognizable clinical signs.
Flavonoid toxicity from dietary sources is not a concern. The quantities in foods and forages are well within safe ranges. Some concentrated flavonoid supplements are available for horses, and these should be used at manufacturer-recommended doses.
