Dentigerous cysts in horses: A retrospective study

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SummaryBackgroundDentigerous cysts are well‐known congenital defects in horses, and the literature on this condition is extensive. Recently, a third type of dentigerous cyst, associated with an exostosis arising from the temporal bone, has been described. Today, computed tomography (CT) is often available and provides detailed information about the exact location and extent of dentigerous cysts, allowing for the description of new findings.Study designThis is a case series outlining the clinical, radiographic and computed tomographic features of dentigerous cysts in seven horses presented to the Equine Clinic at the Vetsuisse Faculty, University of Zurich, Switzerland.ObjectivesThe aim of this case series was to describe the radiographic and computed tomographic findings, and the occurrence of exostoses arising from the temporal bone, in horses with dentigerous cysts.MethodsThe medical records of the Equine Hospital at the University of Zurich were reviewed for horses admitted with dentigerous cysts between 2007 and 2023. Data collected and analysed included patient signalment, clinical history, clinical signs and their duration prior to referral, diagnostic imaging results, treatment and outcomes.ResultsThe most common location for the cysts was the base of the ear, although in one case, the maxillary sinus was involved. Of the seven cases, four were Icelandic horses. CT proved superior to standard radiography for determining the extent and precise location of the cysts, as well as for identifying dental material and exostoses in the temporal region. CT also facilitated detailed surgical planning. All cysts were surgically removed with good long‐term outcomes.Main limitationsOverall, the incidence of dentigerous cysts in horses was low. The relatively high occurrence of dentigerous cysts in Icelandic horses in this study is an interesting finding, though the small sample size calls for further research.ConclusionsTwo of the cases in this series were similar to a recently described variant of a ‘temporal dentigerous cyst associated with an exostosis in the temporal region’ and were closely connected to the bony structure and draining tract.