Major Salivary Gland Examinations of the Donkey (Equus asinus) Using Sectional Anatomy, Computed Tomography and Magnetic Resonance Imaging

ABSTRACT Visualizing the major salivary glands (MSGs) in domestic mammals using plain radiology and identifying damaged their structures is impossible. To accurately display MSGs, the knowledge of normal sectional imaging anatomy is essential for veterinarians, aiding them significantly in identifying the exact relations and position of MSGs; however, no reports on the MSGs sectional imaging anatomy in this species have been made. Objectives This study aimed to evaluate computed tomography (CT), magnetic resonance imaging (MRI) and gross sections of MSGs. Methods Seven healthy adult donkeys were used in this study. The sectioned heads were evaluated by CT and 1.5 Tesla MRI. After imaging, the frozen slab sections were photographed, and identified anatomic structures were matched with structures on corresponding CT and/or MRI images. Results The main topographical anatomy references were the external auditory canal and the digastricus muscle for the parotid salivary gland (PSG), digastricus muscle, body of thyroid cartilage and thyrohyoid muscle for the rostral and caudal lobes of the mandibular salivary gland (MSG) as well as the mylohyoid muscle and tongue for the polystomatic sublingual salivary gland (PSSG). The main CT landmarks for PSG were the external auditory canal, atlas wing and digastricus muscle for the caudal lobe, the body of thyroid cartilage and thyrohyoid muscle for the rostral lobe of MSG and the body of mandible and tongue for PSSG. The consistent MRI landmarks were the external auditory canal, the guttural pouch and maxillary vein for PSG, the body of thyroid cartilage and the thyrohyoid muscle for MSG's rostral lobe. The PSSG was not discerned in MRI. The sectional anatomy and imaging of donkey MSGs were similar to those that have been reported in the horse; the principal difference involved the perforation of the PSG substance in horse by the maxillary vein. Conclusion Labelled transverse cross‐sectional imaging anatomy of the donkey MSGs was produced sequentially as an initial reference to aid in evaluating and interpretating of the sectional imaging studies of these structures in this species.