Lucienne Downs, New South Wales Government District Veterinarian, Central Tablelands Local Land Services
(Previously published online with New South Wales Government Local Land Services)
A severe deficiency of iodine causes a lack of essential thyroid hormone production and the thyroid gland enlarges. The enlarged thyroid gland is called goiter. The swelling occurs in the throat area and can be as large as an orange. Goiter is mainly a disease of lambs and kids, it rarely occurs in calves. Goats have a higher requirement for iodine than other livestock.
Causes of Iodine Deficiency
- It mostly occurs due to insufficient intake of iodine from the pasture.
- Iodine deficiency may also be caused by goitrogens – substances within the feed which inhibit the utilization of dietary iodine. Goitrogens have been detected in some legumes and forage crops, but are considered unlikely to be a significant cause of goiter.