Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Rachitis is a a deficiency disease of the osseous system characterized by an excess of newly formed bone that fails to calcify. The disease is caused by an imbalance of the calcium to phosphorus ratio or a deficiency of either mineral. The presence of vitamin D is an essential factor if there is a major imbalance in the Ca: P ratio.
"Rachitis in a Horse,"
Iowa State University Veterinarian: Vol. 18
, Article 5.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol18/iss2/5