Detection of Oronasal Fistula Using a Fluorescent Water Passing Test

The confirmation of a connection between the oral and nasal cavities provides a definitive diagnosis for an oronasal fistula (ONF). However, visual detection is difficult in patients with small fistulas. This study examined whether fluorescein sodium could be used to detect small ONFs. The study included 25 dogs that underwent dental examination and had confirmed periodontal pockets at the Amica Pet Clinic, Japan, between 2020 and 2022. Saline containing fluorescein sodium was injected into the periodontal pocket, termed a fluorescent "water-passing test," followed by detection of fluid discharge from the external naris using an examination light. Of the 25 dogs, 13 showed symptoms consistent with an ONF and of these, 12 were positive and one was negative on the fluorescent water-passing test. Of the 12 asymptomatic dogs, 3 tested positive and 9 tested negative on the fluorescent water-passing test. The fluorescent water-passing test enhanced visibility and facilitated the detection of small volumes of the discharged fluid. The results of this study confirmed the fluorescent water-passing test was useful for the detection of small ONFs.