Gallbladder mucoceles in dogs: Diagnosis, surgical management, and postoperative care

Introduction

Gallbladder mucoceles are characterized by the accumulation of a thick, immobile, and gelatinous layer of mucus within the gallbladder. Although the exact mechanism for its formation is not completely understood, it has been demonstrated that it is the result of excessive mucus secretion by the gallbladder epithelium. Over time, this mucus becomes dehydrated, adheres to the epithelial lining, and progressively accumulates until it fills the entire lumen. This can ultimately result in an extrahepatic biliary duct obstruction, rupture, and bile peritonitis. Gallbladder mucoceles are most commonly diagnosed in middle-aged to older dogs, and several breeds are known to be over-represented, such as Shetland Sheepdogs and Border Terriers.

Diagnosis

Abdominal ultrasound is necessary to diagnose a gallbladder mucocele. The classic appearance of a gallbladder mucocele is that of a kiwi fruit, reflecting its stellate pattern that occurs due to non-gravity dependent material within the lumen. However, the ultrasonographic appearance of a gallbladder mucocele may vary based on its maturity. Early mucocele formation is characterized by a black rim of mucus attached to the wall of the gallbladder with central mobile or immobile sludge. An immature mucocele will present with ridges of mucus extending from the gallbladder wall with central mobile or immobile sludge. A mature mucocele appears as hypoechoic mucus extending from the wall and nearly obliterating the lumen with a very small volume of central echogenic material (Figure 1). A hypermature mucocele is the more classic appearance, appearing similar to a kiwifruit.

The more serious sequelae of a gallbladder mucocele, rupture of the gallbladder, is challenging to diagnosis with ultrasonography. While some findings, such as a hyperechoic mesentery or abdominal effusion, may be suggestive of rupture, the use of ultrasound for this diagnosis has been shown to have a sensitivity ranging from 56-78%.^1,2 Sampling of any abdominal effusion may aid in this diagnosis by evaluating effusion bilirubin compared to serum. However, some dogs will not expel liquid bile into their abdominal cavity, and a falsely normal peritoneal bilirubin may be found.³ Cytologic evaluation may aid in diagnosis of bile peritonitis, particularly if bilirubin crystals or mucus are seen.

While not solely diagnostic for a gallbladder mucocele, several other clinical pathology abnormalities can be seen in these patients. Dogs often have an inflammatory leukogram, increased hepatocellular and cholestatic enzymes, hypertriglyceridemia, or hypercholesterolemia. Hyperadrenocorticism and hyperthyroidism are thought to play a role in mucocele formation and are commonly seen in these patients.

Treatment options

Cholecystectomy is currently considered the standard treatment for dogs with gallbladder mucoceles. Historically, dogs with incidental gallbladder mucoceles were less likely to undergo surgery — likely contributing to the high mortality rates reported in earlier studies. More recent evidence has demonstrated that elective surgery is associated with significantly fewer intraoperative complications and a perioperative mortality as low as 2%.⁴ In contrast, dogs undergoing surgery for symptomatic gallbladder disease have a reported mortality of 14-32%, highlighting the benefits of early surgical intervention. ^5–7

Laparoscopic cholecystectomy has become increasingly common in recent years and is associated with excellent outcomes. As with other minimally invasive procedures, it offers the benefits of reduced pain, shorter hospitalization, and a faster recovery. In addition, the magnified view provided by laparoscopy allows for enhanced visualization of the cystic duct and extrahepatic biliary tree, facilitating meticulous dissection. While a more technically demanding procedure than other common minimally invasive surgeries, laparoscopic cholecystectomy is associated with a less than 5% conversion rate and a 0-5% mortality rate.^8,9 The incorporation of near infrared fluorescent imaging (NIRF) has further improved the safety of this procedure by enhancing visualization of the biliary anatomy, allowing surgeons to more accurately identify the hepatic ducts and determine the optimal window for cystic duct dissection and ligation. Careful case selection, however, remains essential. Patients with evidence of common bile duct obstruction are considered a relative contraindication to laparoscopic cholecystectomy, dependent on the surgeon’s comfort with intraoperative exploration and cholangiography. Patients with bile peritonitis should not be considered appropriate candidates.

Postoperative management

Patients undergoing elective cholecystectomy often recover rapidly, particularly following a laparoscopic approach, and are often discharged within 24-48 hours. These patients should be maintained on appropriate analgesics — typically pure-mu opioids — and discharged with oral analgesics to be continued in the postoperative timeframe. The majority of these patients do not require postoperative antimicrobials. In contrast, patients with symptomatic gallbladder disease, extrahepatic biliary obstruction, or bile peritonitis can require a more intensive postoperative care and monitoring. These patients can become markedly hypotensive, painful, and require around the clock care.

Intravenous fluids should be provided until patients are eating, and serial monitoring of bilirubin concentrations is recommended. Liver enzymes may transiently increase following surgery and should be interpreted in conjunction with the patient’s clinical status.

Major risks and complications of surgery include bile peritonitis, persistent biliary obstruction, and pancreatitis. Persistent or worsening hyperbilirubinemia, abdominal pain, fever, or hemodynamic instability should prompt investigation for these potential complications.

References

1. Jaffey JA, Graham A, VanEerde E, et al. Gallbladder mucocele: variables associated with outcome and the utility of ultrasonography to identify gallbladder rupture in 219 dogs (2007–2016). J Vet Intern Med. 2018;32(1):195-200. doi:10.1111/jvim.14898

2. Choi J, Kim A, Keh S, Oh J, Kim H, Yoon J. Comparison between ultrasonographic and clinical findings in 43 dogs with gallbladder mucoceles. Vet Radiol Ultrasound. 2014;55(2):202-207. doi:10.1111/vru.12120

3. Aicher KM, Gookin JL, Mathews KG, Stowe DM. Measurement of abdominal fluid bilirubin concentration frequently fails to detect biliary tract rupture in dogs with gallbladder mucocele. J Am Vet Med Assoc. Published online June 10, 2026. doi:10.2460/javma.26.03.0228

4. Youn G, Waschak MJ, Kunkel KAR, Gerard PD. Outcome of elective cholecystectomy for the treatment of gallbladder disease in dogs. J Am Vet Med Assoc. 2018;252(8):970-975. doi:10.2460/javma.252.8.970

5. Pike FS, Berg J, King NW, Penninck DG, Webster CRL. Gallbladder mucocele in dogs: 30 cases (2000–2002). J Am Vet Med Assoc. 2004;224(10):1615-1622. doi:10.2460/javma.2004.224.1615

6. Crews LJ, Feeney DA, Jessen CR, Rose ND, Matise I. Clinical, ultrasonographic, and laboratory findings associated with gallbladder disease and rupture in dogs: 45 cases (1997–2007). J Am Vet Med Assoc. 2009;234(3):359-366. doi:10.2460/javma.234.3.359

7. Mehler SJ, Mayhew PD, Drobatz KJ, Holt DE. Variables associated with outcome in dogs undergoing extrahepatic biliary surgery: 60 cases (1988–2002). Vet Surg. 2004;33(6):644-649. doi:10.1111/j.1532-950X.2004.04087.x

8. Mayhew PD, Mehler SJ, Radhakrishnan A. Laparoscopic cholecystectomy for management of uncomplicated gall bladder mucocele in six dogs. Vet Surg. 2008;37(7):625-630. doi:10.1111/j.1532-950X.2008.00428.x

9. Kanai H, Hagiwara K, Nukaya A, Kondo M, Aso T. Short-term outcome of laparoscopic cholecystectomy for benign gall bladder diseases in 76 dogs. J Vet Med Sci. 2018;80(11):1747-1753. doi:10.1292/jvms.18-0266

Rachel Williams, DVM, DACVS-SA is a clinical assistant professor of small animal surgery at the University of Florida. Her professional interests include urogenital surgery, minimally invasive surgery, as well as wounds and reconstruction.Outside of the operating room, she enjoys being outside with her dogs, gardening, and traveling.