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
A dental fistula may be defined as an abnormal passage leading down to the cavity of an alveolar abscess. Two such cases were observed this summer in the practice of Dr. John Spranklin, of Baltimore, Md. One occurred in a male shepherd dog, six years old, while the other was seen in a four year old, male, wire-hair terrier. Both fistulae had their openings a little below the inner canthus of the left eye with a purulent discharge that had the characteristic odor of dental caries.
Grell, Hans A.
"Dental Fistulae in Canine,"
Iowa State University Veterinarian: Vol. 3
, Article 4.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol3/iss1/4