Iodine Deficiency

Iodine Deficiency Still a Problem in Sheep and Goats

We recently received reports of losses due to iodine deficiency in sheep and goats leading to visible goiter, stillborns, hair/wool loss, and weak lambs and kids. Although there are other factors that can affect thyroid development, iodine deficiency is the most common cause of goiter in the PNW, but is easy to prevent. Most owners may not be providing an adequate source of iodine. To address this: we are rerunning a pertinent article from Spring, 2008:

Swollen necks in kid goats

We recently investigated a herd problem that involved the death of kid goats at 1-2 weeks of age. Many of the kids were born with a symmetrical swelling in the upper neck area. The swelling was confirmed in one kid that died at one day of age to be due to enlarged thyroid glands or goiter (see image). (Knife points to enlarged thyroid glands of a goat kid.) Goiter is the result of either an iodine deficiency or the presence of goiterogens (compounds that interfere with dietary iodine uptake such as those found in the seeds of kale and other Brassica spp.). Often adults in an iodine deficient herd will be normal, though reproductive parameters may decline. However kids will be born with goiter and are typically either stillborn or very weakborn and die shortly after birth. An important differential to consider when presented with ventral cervical swelling in kid goats is thymic enlargement. This condition has been described as “milk neck” and is believed to be a benign enlargement of the thymus associated with milk feeding. Kids with thymic enlargement are otherwise normal, in contrast to those born with goiter. Prevention of goiter involves provision of iodine in a mineral mix or iodized white salt (NaCl). Weekly application of 1ml of 7% tincture of iodine (hard to get these days) during gestation was adequate to prevent goiter in nutritionally deficient goats. Dabbing tincture of iodine in the inguinal area of affected lambs and kids has been advocated, though its efficacy is questionable.

By John Wenz, DVM, MS, FDIU