Abstract
Sminthopsis crassicaudata, imported from a laboratory colony in Australia, originally bred successfully in this country, but 4 months after importation animals began to die with enlarged thyroid glands which were devoid of colloid. Deaths were not prevented until the iodine intake was increased to 60 μg/day. It is possible that this high iodine requirement is in some way related to the mineral content of the soils from whence the animals which formed the nucleus of the Australian colony were obtained.
Spontaneous tumours occur in the species; we observed several animals with uterine polyps and one with a reticulum-cell sarcoma. An X-irradiated animal developed a thyroid carcinoma.