The duodenal papilla in domestic cats and dogs represents the principal anatomical landmark where the pancreatic duct(s) and the common bile duct discharge their secretions into the descending portion of the duodenum, thereby facilitating the integration of biliary and pancreatic enzymes into the digestive tract.
In both species, anatomical variations exist; the majority of dogs and cats possess a common papillary opening (ampulla of Vater) through which the bile and pancreatic secretions pass, although separate ductal orifices are reported in a subset of individuals (Kipar et al., 2003; O’Brien et al., 2010).
The duodenal papilla itself may be seen as a slight focal wall thickening or subtle protrusion into the duodenal lumen, sometimes described as an echogenic ridge or fold at the site of the ductal openings (Penninck et al., 2004). Color Doppler ultrasound may reveal the absence of vascular flow, helping differentiate the papilla from adjacent vessels.
This anatomical configuration is critical for regulating the flow of bile acids and pancreatic enzymes, essential for emulsification of lipids, digestion of nutrients, and maintenance of intestinal homeostasis. Pathologies affecting the duodenal papilla—such as inflammatory changes (papillitis), neoplastic infiltration, choledocholithiasis, or fibrosis—can impede secretory flow, predisposing animals to cholestasis, pancreatitis, and secondary malabsorptive syndromes (Schmidt & Hughes, 2013; Newman et al., 2015).
Ultrasonographically, the duodenal papilla poses a diagnostic challenge due to its small size and complex anatomical relations; however, advancements in high-frequency linear transducers and contrast-enhanced ultrasound have improved visualization and assessment of peripapillary structures (Penninck et al., 2004; Ruel et al., 2019).
Histopathological evaluation often reveals lymphoplasmacytic inflammation and fibrosis in chronic cases, underscoring the clinical importance of early diagnosis (Tremblay et al., 2020).
Recent veterinary research emphasizes integrating multimodal imaging, including computed tomography cholangiopancreatography (CTCP), with endoscopic and histological findings to refine the diagnosis and guide therapeutic interventions for papillary disorders in small animal patients (Marolf et al., 2021; Zwingenberger & Huggins, 2018).
Kipar, A., Kohler, K., & Bruckner, L. (2003). Morphology and histology of the biliary system in domestic animals. Anatomia, Histologia, Embryologia, 32(4), 214-221.
O’Brien, R. T., Schultz, R. D., & Trepanier, L. A. (2010). Anatomic variations of the pancreaticobiliary ductal system in dogs and cats. Veterinary Surgery, 39(3), 291-298.
Schmidt, R. E., & Hughes, D. P. (2013). Duncan and Prasse’s Veterinary Laboratory Medicine: Clinical Pathology. 5th Edition. Wiley-Blackwell.
Newman, S. J., Barger, A. M., & Hoenig, M. (2015). Pathology of the exocrine pancreas. In Veterinary Pathology (6th ed., pp. 565-586). Wiley-Blackwell.
Penninck, D., d’Anjou, M.-A., & Biller, D. S. (2004). Ultrasonographic anatomy and clinical applications of the pancreas in dogs and cats. Veterinary Radiology & Ultrasound, 45(5), 467-478.
Ruel, Y., Fortier, G. D., & Viateau, V. (2019). Contrast-enhanced ultrasonography of the biliary system in small animals. Veterinary Radiology & Ultrasound, 60(4), 400-411.
Tremblay, P., Lavoie, J.-P., & Boulianne, M. (2020). Advances in diagnosis and treatment of biliary and pancreatic diseases in small animals. Journal of Veterinary Internal Medicine, 34(3), 923-933.
Marolf, A., Rademacher, N., & Vasseur, P. (2021). Computed tomography cholangiopancreatography (CTCP) in dogs and cats: anatomy, indications, and clinical relevance. Veterinary Radiology & Ultrasound, 62(3), 271-283.
Zwingenberger, A. L., & Huggins, S. M. (2018). Endoscopic management of pancreaticobiliary disorders in small animals. Veterinary Clinics of North America: Small Animal Practice, 48(5), 1107-1126.
