CANINE MEDICINE
Article reprinted with the permission of DVM360, April 2009, Veterinary Medicine is a
copyrighted publication of Advanstar. Communications inc. All rights reserved.
An Update on Gallbladder
Mucocoeles in Dogs
Apr 01, 2009
By Audrey K. Cook, BVM&S, MRCVS, DACVIM, DECVIM-CA,
Rebecca Quinn, DVM, DACVIM
VETERINARY MEDICINE
Once thought to be rare in dogs, gallbladder
mucocoeles are now frequently diagnosed. And
although primarily thought to be best treated surgically,
mucocoeles may be effectively managed medically in
some patients when caught early.
Before 2000, gallbladder mucocoeles were rarely reported in dogs. However, they are now considered
one of the more common causes of extrahepatic
biliary disease. While gallbladder mucocoeles were
initially treated by cholecystectomy, case-based evidence indicates that some may resolve with medical
therapy.1
In this article, we review gallbladder anatomy and
physiology and discuss the pathophysiology of mucocele development. We also describe the clinical
presentation, diagnosis, and management of dogs
with gallbladder mucocoeles.
Gallbladder Anatomy
The gallbladder is an excretory organ found between
the quadrate and right medial liver lobes. It is pearshaped and composed of a fundus, body, and neck.
From the gallbladder's neck, the hepatic ducts join
the cystic duct to form the common bile duct, which
leads to the duodenum.
The gallbladder wall has five layers: epithelium, mucousa, tunica muscularis externa, tunica serosa, and
tunica adventitia.2
1. The epithelium is simple columnar and highly
absorptive. It plays an important role in gallbladder function because it secretes mucin, immunoglobulins, and acid.
2. The mucousa is a combined layer consisting
of the lamina propria and tunica submucousa.2
These layers of the mucousa are indistinguishable
and contain a dense population of lymphocytes
and plasma cells.
3. The tunica muscularis externa consists of scant,
randomly organized smooth muscle fibers.
4. The tunica serosa is a membranous layer sur-
rounding the gallbladder that faces away from the
liver.
5. The tunica adventitia is the outermost gallbladder
layer and faces the liver.
Gallbladder Functions
The gallbladder plays many important roles in digestive health and function, including storing and concentrating bile. Within the gallbladder, water, electrolytes, lipids, and proteins are absorbed from the bile.
This absorption allows for a five- to 20-time increase
in bile bilirubin and bile salt concentrations. The gallbladder also acidifies bile through epithelial acid secretions and adds mucin to bile by bile acid stimulation of the mucousa.
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