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
For the past several years there has been an increased incidence of a disease that can best be described as a necrotic vulvitis of cattle. The increased incidence is perhaps partly due to an increase in numbers of female feeder calves and heifers in this region. The condition constitutes another reason why farmers and feeders pay more for steers. Some even refuse to feed heifers. Except for one steer, bulls and steers have not been found to show any lesions either about the anus or the external sex organs. Usually milk cows that are turned into the feed lots during the day remain free. Of four farms recently visited the cows were unaffected on three and diseased on the fourth.
McNutt, S. H.
"Necrotic Vulvitis of Cattle,"
Iowa State University Veterinarian: Vol. 2
, Article 2.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol2/iss2/2