Cheek Swelling in Rabbits: CT Features That Distinguish Parotid Sialectasis from Dental Disease

Contrast-Enhanced Computed Tomography Is Helpful for Characterizing Confirmed and Presumed Parotid Sialectasis in Rabbits

Elsa Estoueigt, Christophe Feix, Jenna Richardson, Alexandra Nicolier, Aurélie Le Loc’h, Florence Thierry

Background

Parotid sialectasis, defined as dilation of the salivary duct, is an uncommon condition in rabbits and may be difficult to differentiate clinically from more prevalent causes of cheek swelling, particularly dental abscessation. While computed tomography (CT) is the imaging modality of choice for salivary gland disease in dogs, CT characteristics of parotid sialectasis in rabbits have not been systematically described. Accurate identification of the affected salivary gland and duct is critical for diagnosis and surgical planning. The aim of this study was to describe contrast-enhanced CT features of confirmed and presumed parotid sialectasis in rabbits.

Methods

This single-center, retrospective, descriptive study reviewed pre- and postcontrast CT studies from 21 client-owned rabbits presenting with confirmed or presumed parotid sialectasis between 2019 and 2024. Diagnosis was confirmed by surgery in 10 rabbits, with histopathology available in four cases, and presumed in 11 rabbits based on imaging and clinical findings. CT images were analyzed for lesion laterality, parotid gland and duct anatomy, duct trajectory and extent, attenuation characteristics, contrast enhancement, wall thickness, mineralization, and associated dental, otic, or regional soft tissue abnormalities. Clinical records, bacteriological culture results, and histopathological findings were also reviewed.

Results

Twenty-three parotid duct dilations were identified in 21 rabbits, with most cases being unilateral (19/21) and predominantly right-sided. Dilated ducts were typically tubular, fluid attenuating, and non–contrast-enhancing internally, with thin, smooth, contrast-enhancing walls. Median attenuation of duct contents was consistent with fluid, and most ducts extended from the parotid gland or mandibular ramus to the region of the first maxillary premolar tooth. Segmental and multicameral dilations, including Y-shaped configurations, were occasionally observed. Concomitant dental disease was present in nearly all rabbits. Bacterial cultures were positive in all sampled cases, and histopathology consistently demonstrated chronic sialadenitis with ductal dilation, sometimes associated with intraluminal plant material or hair shafts.

Limitations

The study was limited by its retrospective design and relatively small number of confirmed cases. Not all rabbits underwent surgery or histopathological evaluation, raising the possibility of misclassification in presumed cases. Potential selection bias was present due to recruitment from a single referral center, and catheter-related contrast blooming occasionally limited parotid gland assessment.

Conclusions

Contrast-enhanced CT is a valuable diagnostic tool for characterizing parotid sialectasis in rabbits and for differentiating this condition from more common dental-related cheek swellings. Parotid sialectasis in rabbits is typically characterized by fluid-filled, tubular ductal dilations with thin, contrast-enhancing walls, often extending toward the first maxillary premolar. Infectious sialadenitis and concurrent dental disease are frequent associated findings. CT enables accurate identification of the affected salivary gland and duct, supporting appropriate case management and surgical planning.

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