Supplemental iodine as a key to reproduction in pandas?

Pandas are endemic to iodine-poor environments and appear to be specialized for a goitrogenic staple diet. In particular, the importance of thiocyanate in bamboos might possibly have been overlooked in captive breeding programs. Although excreted in urine, thiocyanate first antagonizes absorption of iodine by the thyroid (of parent, fetus and suckling juveniles) and the mammary glands. In livestock and humans, subclinical deficiency of iodine is known to result in reproductive problems (including retardation of the fetus and suckling infant) even where the mother appears to be unaffected beyond slight hyperplasia of the thyroid and subtle hypothyroidism as reflected by levels of thyroid hormones. We suggest that the possibilities of iodine deficiency or excess should be carefully considered wherever the reproductive rates of pandas are unsatisfactory.