Preoperative diagnostic tests, including a complete blood count, serum chemistry profile, urinalysis, and coagulation panel, are indicated. Treat all patients with appropriate intravenous fluids, and any electrolyte derangements must be addressed before surgery. Vitamin K1 therapy is also recommended (Table 2) in all dogs, even if the results of preoperative coagulation panels are normal.21 Start subcutaneous vitamin K1 therapy 24 hours before surgery to allow adequate time for the production of vitamin K-dependent coagulation factors. Continue therapy until bile flow is normal, typically two to four days after surgery.
Table 2: Drugs Commonly Used in the Perioperative and Medical Management of Dogs with Gallbladder Mucoceles
During surgery, a complete abdominal exploratory is recommended so that concurrent or occult problems can be identified and addressed. While several surgical techniques are described, cholecystectomy has many advantages, as removal of the gallbladder prohibits secondary gallbladder infection and rupture.18 Other surgeries that have been described include cholecystotomy, cholecystoduodenostomy, and cholecystojejunostomy.25 Cholecystotomy is a suboptimal choice given the disease process and possible associated gallbladder wall compromise.
The surgical evaluation should also include expressing or cannulating the common bile duct, performing liver biopsy, and collecting bile and liver samples for aerobic and anaerobic culture. In patients with biliary rupture, extensively flush the peritoneal cavity, and place abdominal drains.
Perioperative care includes broad-spectrum antibiotics (adjusted based on culture results), hepatoprotectants, and a low-fat diet. The most common complications of cholecystectomy include pancreatitis and bile peritonitis; death is also common.14,17,18 Chronic vomiting occurs infrequently. The perioperative mortality rate associated with cholecystectomy is moderate, with 22% to 40% of patients dying within 14 days of surgery.14,17,18 Patients that survive this period have excellent long-term survival rates. In general, the morbidity and mortality rates of patients with extrahepatic biliary duct obstruction undergoing biliary diversion procedures are higher than those undergoing cholecystotomy.26 Unfortunately, no reliable predictors for survival exist.
To date, no prospective studies have been completed regarding the risks associated with medical management of mucoceles. Medical management can be considered in asymptomatic and mildly symptomatic patients without evidence of extrahepatic biliary duct obstruction or gallbladder rupture, as long as the clinician and client are aware of the potential complications.1,21
Antibiotics. Because some mucoceles are associated with bacterial infection, performing an ultrasound-guided cholecystocentesis to obtain a sample for aerobic and anaerobic bacterial culture is recommended. Although considered relatively safe, rare complications of percutaneous cholecystocentesis may include bile leakage, bradycardia due to a vasovagal reaction, bacteremia, and local hemorrhage.27,28 Studies have indicated that risks associated with percutaneous cholecystocentesis in normal dogs and those with cholecystitis are minimal, but complication rates have not been determined in dogs with mucoceles.27,29
If bacteria are isolated, a six- to eight-week course of antibiotics is recommended. Gram-negative anaerobes are the most common bacteria isolated, but infections may be mixed. For this reason, antibiotic therapy with a combination of two medications is often pursued. In cases in which ultrasound-guided cholecystocentesis is not feasible, empirical antibiotic therapy should be prescribed (Table 2).21 Use caution when prescribing antibiotics in patients with hepatic insufficiency since they may be unable to metabolize certain antibiotics appropriately.
Choleretics. Choleretics, drugs that stimulate hepatic bile excretion, should be administered (Table 2). Ursodiol (ursodeoxycholic acid) is a naturally occurring bile acid that increases bile flow by decreasing the cholesterol content of bile and thinning biliary secretions by producing bicarbonate-rich enhanced bile flow. Ursodiol is also considered hepatoprotective since it reduces the hepatotoxic effects of bile salts and protects liver cells from endogenous hydrophobic bile acids such as lithocholate and deoxycholate.30 It is important to note that ursodiol is contraindicated in cases of extrahepatic biliary duct obstruction. Anecdotally, mucoceles have recurred after ursodiol discontinuation.