Gallbladder mucocele with secondary or concurrent acute pancreatitis

Physical examination
She was nervous and in good body condition. Her abdomen was somewhat tense and palpation suggested pain in her cranioventral abdomen.

Laboratory data

Hematology
A CBC and blood film review performed on the LaserCyte® Hematology Analyzer were unremarkable.

Additional Diagnostics—Abdominal Ultrasound:

Figure 1: Transverse ultrasound image of gallbladder. The gallbladder is moderately distended, with a moderate amount of hyperechoic material within. Hyperechoic striations extending to the gallbladder wall give the gallbladder a "kiwi fruit" appearance.

Discussion

GGT serves as a specific indicator of cholestatic disease with or without increases in other laboratory values such as ALKP, TBIL and CHOL. In the dog, a mild increase in ALKP (less than 3-4 fold increase above the upper reference interval limit) is nonspecific and may be due to cholestasis, enzyme induction by something like glucocorticoids or increases associated with bone or gastrointestinal disease. Without GGT in this case, identification of cholestatic liver disease would be impossible. Although both ALKP and GGT can support the presence of cholestasis, they demonstrate differing degrees of sensitivity and different patterns of increase may provide insight into different pathologic processes. Increases primarily in GGT support posthepatic cholestasis and diseases of the gallbladder and periportal regions of the liver; increases primarily in ALKP support disease within the hepatic parenchyma. Even mild-to-moderate increases of GGT without other laboratory evidence of cholestasis or clinical signs of disease should be considered significant and further diagnostics, such as abdominal imaging, are indicated. Increases in GGT above 10 u/L in dogs (7 u/L in cats) should be considered significant.

In Rachel's case, there is decreased calcium and an increased lipase; this combination is consistent with canine pancreatitis; however, the lipase in this case is only minimally increased—slightly greater than the high reference interval limit. A three-fold increase of lipase above the reference interval limit is strongly supportive of pancreatitis, but the degree of increase in Rachel's case, without knowledge of baseline lipase levels during wellness, is typically considered insignificant. Fortunately, Rachel's veterinarian had access to laboratory values trended from prior annual wellness visits. Although minimally increased in this case, the lipase value of 950 u/L represented a significant increase over Rachel's most recent wellness value of 458 u/L; this finding is strongly supportive of possible pancreatitis and further investigation is warranted. The severe increase in GGT with a mild nonspecific increase in ALKP is suggestive of a posthepatic obstructive or biliary disease, which is also potentially seen with pancreatitis. Rachel also had an increased chloride and although this is a very mild increase, it is significantly increased relative to sodium, which is suggestive of a significant acid-base disturbance (secretional metabolic acidosis).

Based on these significant laboratory findings, her veterinarian recommended further diagnostics, which included abdominal radiographs and ultrasound and canine-specific pancreatic lipase testing (SNAP® cPL™ Test and/or Spec cPL® Test), which were consistent with pancreatitis. Abdominal imaging revealed her pancreas to be moderately enlarged and irregular and surrounded by echogenic tissue and a small amount of peritoneal fluid. The duodenum was fluid-filled but the walls were of normal thickness and echogenicity. In addition to these changes, an echogenic, irregular "kiwi"-like mass was identified within the gallbladder lumen and mild distention of the common bile duct was noted.

Diagnosis Summary

Gallbladder mucocele with secondary or concurrent acute pancreatitis.

Gallbladder mucoceles, once rarely diagnosed, are now known to be a relatively common cause of extrahepatic biliary disease in dogs. Patients with gallbladder mucoceles typically have a history of vague nonspecific clinical signs including vomiting, anorexia and lethargy.

Rachel responded well to therapy for acute pancreatitis. Cholecytectomy for the gallbladder mucocele, performed 6 weeks later, was curative in Rachel's case. All her laboratory values had returned to those of her last wellness values—within reference interval limits—2 weeks postoperatively and she continues to be much improved, clinically. There has been no recurrence of clinical signs suggestive of pancreatitis.

With Rachel, because her clinical signs were nonspecific, performing a Chem 17 with electrolytes on the Catalyst Dx® Chemistry Analyzer provided her veterinarian with valuable diagnostic information that would not have been available from a VetScan® Comprehensive Panel. The Catalyst Chem 17 CLIP including GGT, lipase and electrolytes, helped facilitate a rapid diagnosis of a gallbladder mucocele with complicating pancreatitis, which could have been delayed or missed altogether without the benefit of rapid results. Furthermore, knowledge of her electrolyte imbalances as provided by the Catalyst Dx analyzer, unlike with the VetScan analyzer, allowed for the best possible choice of fluid and supportive therapy facilitating her rapid recovery.