New CT Reference Standards for Feline Pancreatic Ducts Established in 78 Healthy Cats

Measurements and Visibility of the Pancreatic Ducts on Computed Tomography in 78 Cats Without Clinical Evidence of Pancreatitis

Abby Caine, Man-Hei Ma, Mike Herrtage, Tim Sparks, Marie Aude Genain

Background

Pancreatic disease is common in cats, yet diagnosis is challenging due to nonspecific clinical signs and limitations of laboratory and ultrasound findings. Prior studies suggest variability in pancreatic duct size with age and disease, but CT reference values have been evaluated only in small populations. This study addresses the need for comprehensive normal CT measurements of feline pancreatic ducts and duodenal papilla in a large cohort of cats without clinical or biochemical evidence of pancreatitis. The authors hypothesized that most duct segments would be visible on CT and that visibility would improve with contrast administration.

Methods

This retrospective study evaluated CT images from 78 cats drawn from two veterinary institutions. All included cats had normal DGGR lipase and no clinical, biochemical, or imaging evidence of pancreatic disease. Pre- and post-contrast CT images were analyzed by two reviewers using multiplanar reconstructions. Measurements included diameters of left, right, and common pancreatic ducts; duodenal papilla dimensions; and pancreatic parenchyma thickness and Hounsfield units. Visibility of each structure was scored via a 5-point Likert scale. Inter- and intra-observer agreement was assessed through intraclass correlation coefficients, and statistical comparisons used Wilcoxon and Mann–Whitney testing.

Results

Across all cats, mean pancreatic duct widths were 1.4 mm (left), 1.1 mm (right), and 1.6 mm (common). Post-contrast imaging substantially improved visibility, reducing the proportion of non-visible ducts to 3% (left), 22% (right), and 20% (common). The duodenal papilla averaged 2.8 mm in diameter and was not visible in only 6% of post-contrast scans. Pancreatic parenchyma thickness averaged 6.9 mm (left limb) and 5.8 mm (right limb). No mineralization or duct wall irregularities were detected. Older cats (≥10 years) did not differ significantly from younger cats in duct measurements.

Limitations

Use of multiple CT scanners may have introduced variability in image resolution, particularly for structures near the limits of detectability. As a retrospective study, historical pancreatic disease could not be fully excluded despite normal clinical and biochemical findings. Given the known high prevalence of subclinical pancreatitis in the general cat population, some cats could theoretically have had unrecognized chronic disease.

Conclusions

CT imaging enables consistent visualization of feline pancreatic ducts, especially after contrast administration. The left pancreatic duct is most reliably identified, whereas the right and common ducts are visible in a majority but not all cases. The study establishes reference CT measurements for pancreatic ducts and the duodenal papilla in cats without clinical evidence of pancreatitis, with no significant differences between younger and older cats. These normative data support improved diagnostic interpretation of feline pancreatic CT studies.

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