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 Nov. 18, 1943, a 3-year-old sorrel gelding was brought to the Stange Memorial Clinic with the history of difficult breathing. Upon examination it was found that the left nostril would pass very little air, and a loud snoring sound was emitted when the animal was excited. Attempts at locating and determining the nature of the obstruction were unsuccessful because it was too far back in the nasal cavity. A stomach tube could be passed about 6 or 7 in. into the nose before being stopped. The horse was placed on the operating table and probing revealed a soft structure in the cavity. Thinking it might be a foreign body, the operator passed a Knowle's forceps which ruptured a cyst containing considerable serous fluid of a deep orange color. The nostril could then pass two-thirds the normal amount of air. It was thought that the cyst would perhaps continue to drain and then heal, but the next morning the left nasal passage again was almost completely occluded.
Engelbrecht, H. J.
"Removal of a Nasal Obstruction,"
Iowa State University Veterinarian: Vol. 6
, Article 9.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol6/iss3/9