Too little Iodine
Iodine (I) is required for the formation of thyroid hormones (thyroxine) which control the metabolic rate of all animals. Iodine deficiency leads to goiter and reduces metabolic rate.
Foals born to mares with iodine deficiency or a deficient supply of iodine may be weak or stillborn.
Solutions: Good sources of iodine are seaweed, fishmeal, commercial concentrates (where iodized salts are commonly used) and common mineral mixes.
Too much Iodine
Over feeding of iodine (I) may cause fetal damage or lead to weakly or stillborn foals.
Solutions: Reduce the feeding of mineral mixtures with iodine, avoid iodized salt and avoid supplements which contain marine algae (seaweed).