Iodine & Horses

Iodine. It’s an essential trace mineral in our horse’s diets which plays many crucial roles. It is vital as a constituent of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Every cell in the body depends upon thyroid hormones for regulation of their metabolism, hence its crucial role in not only metabolic rate and body condition but also fertility and growth. Iodine also plays a role in immune function and the integrity of nerve cells and their ability to communicate signals throughout the nervous system of the body.

Many regions in the world have insufficient iodine levels in the soil. Iodine deficient soils are most common in inland regions, mountainous areas and areas of frequent flooding, but can also occur in coastal regions. Unless horse diets are adequately supplemented, equines that graze on pastures in these regions and/or consume hay and feed crops grown in these areas, are likely to fall well short of their minimal iodine requirements. Research has also demonstrated reduced uptake of iodine by pastures which have been grown with high levels of nitrogen fertilisers, even in soils with otherwise reasonable iodine levels.

Like many minerals however, too much iodine can be just as problematic as too little iodine. Many signs, symptoms and health consequences of iodine excess often mimic those of iodine deficiency. An important reminder that more is not better, and hap hazardous supplementation can be detrimental to horse health and fertility.

The most common and innocent mistake made in relation to supplementation of iodine is the use of seaweed supplements- commonly resulting in iodine excess.