Case Review

Medical History

Breed: Pomeranian

Age: 4 years old

Gender: Male(neutered)

Ultrasound Findings

The gallbladder appeared moderately distended.

A radiating echogenic structure was observed within the lumen, forming a “stellate pattern”.

No signs of gallbladder wall thickening, perforation, or pericholecystic fluid were noted.

Did You Know

Gallbladder Mucocele？

What Is the gallbladder and what does it do?

Thegallbladder is a small organ that stores and concentrates bile produced by theliver. Bile helps emulsify fats during digestion.

What Is a GBM？

A GBM isan abnormal accumulation of thick, gelatinousmucus within the gallbladder, leading to its distension and oftenobstructing bile outflow.

What causes GBM?

While theexact pathogenesis is unclear, multiple factors are associated:

l Endocrine diseases, such as Cushing’s syndrome or hypothyroidism

l Hyperlipidemia

l Gallbladder dysmotility

l Genetic predisposition

Which breeds are at risk？

GBM is more common in purebred dogs, especially:

l Miniature Schnauzers

l Shetland Sheepdogs

l Border Terriers

l Beagles

Why is it dangerous？

Left untreated, a GBM can lead to:

l Aseptic or septic cholecystitis

l Gallbladder wall necrosis

l Gallbladder rupture, causing bile peritonitis

l Systemic Inflammatory Response Syndrome (SIRS)

Early-stage GBMs may be asymptomatic, making imaging-based screening vital in at-risk dogs.

Potential outcomes of mucocele formation？

Four clinical outcomes of mucocele formation. 

A—Gallbladder wall infarction and necrosis. 

B—Secondary bacterial infection leading to superimposed cholecystitis. 

C—Extrahepatic bile duct obstruction by mucus plugs. 

D—Progressive accumulation of mucus leading to rupture under pressure.

Picture from JAVMA I JUNE 2025| VOL 263| NO.6

Why Ultrasound Is Key in Diagnosis

Ultrasound is the gold standard for non-invasive diagnosis of GBM. It enables:

l Real-time visualization of gallbladder shape and internal content

l Identification of characteristic patterns and structural changes

l Early detection before rupture or infection develops

Six Classic Sonographic Patterns of GBM

Disease Progression Under Ultrasound？

l Early Stage: Mild mucin attachment to the gallbladder wall

l Immature Stage: Mucosal ridges projecting inward

l Mature Stage: Nearly complete obstruction of the lumen by mucin

l Overmature Stage: Dense, radiating echogenic streaks throughout the gallbladder

These changes are easily tracked over time using high-quality ultrasound, guiding decisions between conservative management and surgical intervention.

Simplified schematic of ultrasonographic progression of mucocele formation. A—Early mucocele formation: hypoechoic (black) rim of mucus attached to the gallbladder wall with central echogenic mobile or immobile sludge. B—Immature mucocele: ridges of hypoechoic mucus extending from and attached to the gallbladder wall with central echogenic mobile or immobile sludge. C—Mature mucocele:hypoechoic mucus attached to the gallbladder wall and nearly obliterating the gallbladder lumen with a small volume of central echogenic mobile or immobile sludge. D—Hypermature mucocele: highly compressed hypoechoic mucus obliterating the gallbladder lumen with fine hyperechoic striations radiating centrally.(Picture from JAVMA I JUNE 2025| VOL 263| NO.6)

Gallbladder mucocele is a serious but often silent threat to canine health.

Ultrasound imaging plays a central role in both early detection and ongoing assessment, helping clinicians visualize patterns like the stellate sign before life-threateningcomplications arise.

With advanced imaging technologies, CHISON VET is committed to empoweringveterinary professionals with clarity, precision, and care—supporting animal health, one scan at a time.

CHISONMEDICAL

References

1. Aguire AL, Center SA, Randolph JF, et al. Gallbladder disease in Shetland Sheepdogs: 38 cases (1995–2005). J Am Vet Med Assoc 231:79–88, 2007.

2. Amellem PM, Seim HB, MacPhail CM, et al. Long-term survival and risk factors associated with biliary surgery in dogs: 34 cases (1994–2004). J Am Vet Med Assoc 229:1451–1457, 2006.

3.Mehler SJ, Mayhew PD, Drobatz KJ and Holt DE. Variables associated with outcome in dogs undergoing extrahepatic biliary surgery: 60 Cases (1988–2002). Veterinary Surgery 33:644–649, 2004.

4.Pike FS, Berg J, King NW, et al. Gallbladder mucocele in dogs: 30 cases (2000–2002). J Am Vet Med Assoc 224:1615–1622, 2004.

5.Worley, DR, Hottinger Lawrence HJ. Surgical management of gallbladder mucoceles in dogs: 22 cases (1999–2003). J Am Vet Med Assoc 225:1418–1422, 2004.

6.Neer TM. A Review of disorders of the gallbladder and extrahepatic biliary Tract in the dog and cat. Journal of Veterinary Internal Medicine 6:186-192,1992.

7.Gall Bladder Mucocele in the Dog- Diagnosis and Medical Management,by Julie Stegeman, DVM, DACVIM, Nashville Veterinary Specialists - Clarksville

8.Canine Gallbladder Mucocele,BySharon A. Center, DVM, DACVIM, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University

9.Diagnosis and management of gallbladder mucocele formation in dogs Jody L. Gookin

10.Diagnosis and management of gallbladder mucocele

formation in dogs, Jody L. Gookin, DVM, PhD, DACVIM1* ; Kyle G. Mathews, DVM, MS, DACVS; Gabriela Seiler, DVM, DACVR

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