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
On September 16, 1959, six Shetland ponies were admitted to the I.S.U. Veterinary Clinic. These ponies were from a band of thirty animals that had been sold and shipped to an eastern state in the spring. When returned here the animals all were in poor condition, and had a history of having "shipping fever" all summer. Examination showed all animals to be infected with strongyles. A standard therapeutic dose of phenothiazine was administered to the animals. No hemoglobin determination was made prior to treatment.
Hunt, J. A.
"Phenothiazine Toxicity in a Group of Shetland Ponies,"
Iowa State University Veterinarian: Vol. 22
, Article 11.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol22/iss1/11