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 Oct. 22, 1946, a Holstein cow was admitted to Stange Memorial Clinic. The owner had found the animal bloated 8 days before and at that time he had tapped the rumen with a butcher knife. The wound in the abdominal wall did not heal so the owner sought professional aid for the cow.
Iowa State University Veterinarian: Vol. 9
, Article 9.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol9/iss3/9