Dilation of the pancreatic duct has been described as an ultrasonographic feature of pancreatitis in cats. The purpose of this study was to determine normal pancreatic duct width in healthy older cats and assess the significance of pancreatic duct dilation observed in a clinical population. In a prospective study, pancreatic ultrasound was performed in 15 healthy cats (mean age 13 +/- 3 years). Mean pancreatic width of left lobe, body, and right lobe was 0.65 +/- 0.16 cm (0.46-1.03 cm), 0.64 +/- 0.14 cm (0.46-0.9 cm), and 0.43 +/- 0.09 cm (0.3-0.57 cm), respectively. Mean pancreatic duct width was 0.13 +/- 0.04 cm (0.06-0.24 cm), which was significantly larger than previously reported for younger cats (0.08 +/- 0.025 cm) (P < 0.001). One hundred and four of 1445 clinical patients (7.2%) were diagnosed with a dilated pancreatic duct and were reviewed in a retrospective study. Incidence of pancreatic duct dilation was significantly higher in older than in younger cats (2.7% in cats < 1-5 years vs. 18.1% in cats 15 years or older; P < 0.001). Mean pancreatic duct width was 0.23 +/- 0.07 cm (0.14-0.52 cm), and there was a significant correlation between age and pancreatic duct width (P = 0.01). There was also a significant relationship between the mean ratio of pancreatic duct width and pancreatic thickness (n = 98) (0.29 +/- 0.09; 0.09-0.58; P = 0.041). There was no significant difference in age between cats with and without pancreatic disease. There was no association between pancreatic disease and pancreatic duct width or pancreatic duct width/pancreatic thickness ratio. Pancreatic duct width and pancreatic duct width/pancreatic thickness ratio in cats are significantly associated with age.