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 February 9, 1945, a 10-year-old sorrel mare was brought to the Stange Memorial Clinic with a diagnosis of alveolar periostitis. Tne horse had a swelling in the left mandibular area similar to one caused by an infected tooth. A speculum was placed in the horse's mouth but there was so much swelling that an examination was impossible. The swollen area was hot packed for the next 4 days to reduce the swelling, and then the mare was given one and one-half ounces of chloral hydrate via a stomach tube as a basal sedative and restrained on the operating table. A speculum was placed in the mouth to facilitate palpation to determine which tooth was involved. It was at this time that the swelling was found to be due to an abscess in the cheek and not an infected tooth. The mucous membrane of the cheek was forced between the teeth by the swelling so mastication was extremely painful. It was decided to drain the abscess to the outside, to avoid packing of the abscess cavity with food if opened to the inside of the mouth, with resulting delay in healing.
Arnold, James R.
"An Abscess in the Mandibular Area of the Horse,"
Iowa State University Veterinarian: Vol. 7
, Article 10.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol7/iss4/10