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
Last December 12, a colt 7 months old was admitted to the Iowa State College Veterinary Clinic. The animal had an extra digit on the medial side of the left front foot. This caused very little trouble as far as walking was concerned, but was unsightly and probably would have interfered more as the colt grew older.
Cook, Leon W.
Iowa State University Veterinarian: Vol. 2
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol2/iss2/4