Sedation with dexmedetomidine is associated with transient gallbladder wall thickening and peritoneal effusion in some dogs undergoing abdominal ultrasonography

Computed tomographic reference ranges of intrathoracic caudal vena cava ratios in sedated adult dogs without cardiac, pulmonary, or hypovolemic disease

BACKGROUND

Radiographic assessment of the intrathoracic caudal vena cava (CVC) is commonly used to evaluate hemodynamic status in veterinary patients without and with pulmonary, pericardial, or right-sided cardiac diseases. Many of these patients are now commonly evaluated with computed tomography (CT) in both emergency and referral settings. Traditional radiographic ratios in dogs, particularly the CVC height/aorta height (CVC/Ao) ratio, are often extrapolated to CT in order to determine if the CVC is normal in size.

OBJECTIVES

The first goal of this retrospective study was to create an objective measurement method to evaluate the size of the CVC via CT. The second goal was to report normal CVC ratio values in both sagittal and transverse CT images.

METHODS

The traditional lateral radiographic CVC ratios were extrapolated to similar ratios obtained from sagittal CT images in stable, sedated adult canine patients without known cardiac or pulmonary disease. Additionally, new methods of canine CVC ratios using transverse CT images were defined using vessel height and area. Mean, standard deviation, and 95% confidence intervals (CIs) of the CVC ratios in transverse and sagittal CT images were calculated to determine normal reference ranges.

RESULTS

Ratio agreement from observers of different skill levels was moderate to excellent. Sagittal CT CVC/Ao mean was 1.07 ± 0.17 with a CI of 0.71.42. The mean and CI of transverse CT CVC/Ao height and area were 1.14 ± 0.27 and 0.781.44 and 1.36 ± 0.59 and 0.641.94, respectively.

CONCLUSIONS

Application of normal sagittal and transverse CT ratio values in canine patients with and without hypotension, pulmonary, pericardial, or right-sided cardiac diseases is necessary to determine the clinical usefulness of these ratios.

Ultrasonographic features of gallbladder wall thickening in dogs with hypoalbuminemia

Hypoalbuminemia has been considered as a cause of gallbladder wall thickening in humans and dogs. Recent study revealed that gallbladder wall thickening in dogs with hypoalbuminemia may not be associated with serum albumin/plasma levels within 48 h of ultrasound study. However, gallbladder wall edema may change within 48 h, and the ultrasonographic features of gallbladder wall thickening in dogs with hypoalbuminemia have not been reported. The purpose of this study is to describe the relationship between serum albumin levels within 24 h of ultrasound and gallbladder wall thickening, and to describe the ultrasonographic features of thickened gallbladder walls in dogs with hypoalbuminemia. 37 hypoalbuminemic dogs with gallbladder ultrasound images were retrospectively included. Ultrasound studies were reviewed, and gallbladder wall thickness, layering appearance, echogenicity, echotexture, distribution, evidence of gallbladder mucocele, and presence of peritoneal effusion were recorded. Additionally, serum albumin levels within 24 h of ultrasound study and the administerd sedation were recorded. The prevalence of gallbladder wall thickening in dogs with hypoalbuminemia was 13.5%. The 3-layer appearance of the gallbladder wall was observed in 4 dogs, and a single-layer gallbladder wall thickening in one dog. Diffuse thickening was observed in all 5 dogs. The serum albumin level of dogs with gallbladder wall thickening was not different (p = 0.14) from dogs without thickening. Gallbladder wall thickening was not common, occurring only with mild hypoalbuminemia, and was commonly associated with a 3-layer appearance and considered as gallbladder wall subserosal edema. Causes other than hypoalbuminemia may be responsible for thickening of the gallbladder wall in dogs with hypoalbuminemia.

Ultrasonographic measurement of gallbladder wall thickness in fasted dogs without signs of hepatobiliary disease

BACKGROUND

Ultrasound-determined gallbladder wall thickness is widely used to aid in the diagnosis of gallbladder disease, but no reference values supported by published measurement data are available in dogs.

HYPOTHESIS/OBJECTIVE

Establish normal thickness of the gallbladder wall in dogs.

ANIMALS

Fifty-three dogs presented to a referral hospital and required abdominal ultrasound examination for reasons unrelated to primary hepatobiliary disease.

METHODS

Cross-sectional observational study recruiting dogs requiring abdominal ultrasound examination. A standard sequence of gallbladder wall images was recorded for later review. Inclusion criteria were normal ultrasonographic hepatobiliary, pancreatic, and small intestinal findings. Exclusion was determined by 2 European College of Veterinary Internal Medicine (ECVIM)-certified veterinary internists blinded to gallbladder wall thickness data. Dogs were excluded if they had inadequate medical records, a previous history of hepatobiliary, gastrointestinal, or pancreatic disease likely to impact the biliary system (eg, chronic vomiting, nausea, jaundice, diarrhea), unexplained increases in liver enzyme activities, hypoalbuminemia, or ascites. Gallbladder wall thickness was determined by 2 European College of Veterinary Diagnostic Imaging (ECVDI)-certified veterinary radiologists working together to generate a consensus for each dog. The final output was the maximum normal wall thickness for this population of dogs.

RESULTS

The upper limit for gallbladder wall thickness in 53 fasted (8 hours) dogs <40 kg was 1.30 mm (90% confidence interval, 1.19-1.41).

CONCLUSIONS AND CLINICAL IMPORTANCE

Normal gallbladder wall thickness in dogs is lower than previously reported. Additional studies are required to determine potential effects of body weight and the optimal cut-off to distinguish between healthy and diseased gallbladders.