A goiter is defined as any enlargement of the thyroid gland. Goiter is a condition usually found in iodine-deficient areas of the country. Iodine-deficient areas are found in the Great Lake region, Northwestern states, Northern plains region of the United States and Canada, extending from the Great Lakes to the Rockies. Therefore goiter is a relatively rare condition among the domesticated animals around Ames, Iowa.
Venzke, W. G. and Mannasmith, C. H.
"Colloid Goiter and Its Incidence Among Adult Horses,"
Iowa State University Veterinarian: Vol. 3
, Article 8.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol3/iss1/8