Background: Increased gallbladder wall thickness has been documented ultrasonographically in dogs with cholecystitis, although the optimal cut-off value is unclear. A recent study established an upper limit for normal gallbladder wall thickness in dogs ( < 40kg) of 1.30 mm. Hypothesis/
Objectives: To compare diagnostic performance of this recently proposed upper reference limit for gallbladder wall thickness (1.30 mm) to the historically accepted value (3 mm) for identification of canine bactibilia. Animals: 205 client-owned dogs.
Methods: A multicenter diagnostic study with retrospective and prospective inclusion of cases. Inclusion criteria: availability of standardized gallbladder ultrasonographic images and bile sampling. Exclusion criteria: inadequate medical records, poor image quality, recent blood/plasma transfusion ( < 5 days), bodyweight > 40kg. Gallbladder wall thickness was determined twice each by two ECVDI specialists. The imager with the lowest intra-observer variability was selected as the reference observer; the higher of their measurements used for analysis. The proportion of correctly confirmed bactibilia cases was calculated for each reference value.
Results: Among dogs with and without bactibilia respectively, 22 and 76 had measurements < 1.30 mm, 41 and 66 were > 1.30 mm, 60 and 131 were < 3 mm, and 3 and 11 were > 3 mm. The 1.30 mm reference value yielded moderate sensitivity (65.1%) and poor-moderate specificity (53.5%) for the identification of bactibilia, whereas the 3 mm threshold yielded very poor sensitivity (4.8%) but high specificity (92.3%). Conclusions/clinical importance: The 1.30 mm threshold offers superior sensitivity. The trade-off is lower specificity; likely justified given the clinical priority to maximize case detection and appropriate management.
