Gross and Computed Tomographic Anatomy of the Lacrimal Drainage System of Snakes
Nicole M. Souza, BS; David J. Maggs, BVSc (hons), DACVO; Shin Ae Park, DVM, PhD; Sarah Puchalski, DVM, DACVR; Christopher M. Reilly, DVM, ACVP; Joanne Paul-Murphy, DVM, DACZM; Christopher J. Murphy, DVM, PhD, DACVO
Objective: Unique anatomic characteristics of the lacrimal drainage system in snakes may predispose them to obstruction with subsequent clinical complications including distension of the subspectacular space (pseudobuphthalmos) or infection (subspectacular abscessation). This study was designed to define lacrimal duct anatomy in snakes.
Animals studied: Twenty snakes of 10 different species.
Procedures: Direct observation following injection of fluorescein into the subspectacular space, microtomographic imaging following injection of one of three contrast agents into the subspectacular space, gross dissections following injection of latex into the subspectacular space, and histopathologic observations.
Results: Microtomographic imaging following postmortem injection of barium provided the clearest images. Fluorescein and iodinated contrast agents were not useful. Microtomographic images and gross dissections revealed a single mucosal opening into the lacrimal duct through the ventronasal palpebral-conjunctival space (in the region of the ventral orbital rim). The lacrimal duct then passed in a rostral and ventral direction through a prefrontal foramen. It completed two 90° turns as it passed between the vomer and hypochoanal cartilage before entering the medial aspect of the Jacobsen’s organ duct mouth at the rostral aspect of the palate. Of the nine additional snake species dissected, specimens fell into one of three groups based on similar anatomic characteristics of the lacrimal duct: Python regius, Boa constrictor, Lampropeltis calligaster.
Conclusion: This study is the first to utilize 3D reconstruction of micro CT images to provide an accurate anatomic representation of the lacrimal duct of boid snakes with barium contrast while identifying the challenges faced with current imaging modalities.