Cholelithiasis

Also known as: Biliary calculi — Gallstones — Gall Stones — Choleliths — Cholecystolithiasis — Choledocholithiasis

Introduction

Cholelithiasis is rare but occurs in all animals.

Choleliths may be of minute size, like grains of sand, or they may be large and solitary.

In dogs and cats, most stones consist of calcium salts and bilirubinate (pigment stones).

Stones vary in weight and fragility depending upon their composition. They are sometimes concentrically laminated and often faceted. They are composed of a varying mixtures of materials to include salts of bilirubin, calcium carbonate, calcium phosphate and glycoproteins.

When stones occur in the gallbladder this is called cholecystolithiasis, and when they occur in the bile duct it is called choledocholithiasis.

Pathogenesis

Potential causes include:

bile stasis

cholecystitis

change in bile composition

Stones can form in the absence of infection, but clinical disease usually results when the biliary system containing stones becomes infected or obstructed.

Dogs with pigment gallstones suffer from gallbladder inflammation and mucus hypersecretion from soluble factors in the bile that inflame the gallbladder wall.

Clinical Signs

Cholelithiasis is often asymptomatic.

Clinical disease presents as: jaundice, vomiting, anorexia, weight loss and dehydration.

Signs may be mild, transitory or recurrent.

Acholic faeces indicate complete bile duct obstruction, which can lead to persistent abdominal pain.

Diagnosis

Cholelithiasis should be considered as a possible diagnosis if obstructive icterus is present.

Radiography: will detect radioopaque calculi (50% at most)

Ultrasonography: will detect radiolucent calculi and enables examination of the liver parenchyma.

Haematology and biochemistry reveal extrahepatic biliary tract obstruction: raised AST and ALP, increased bilirubin.

Treatment

Animals may need no treatment if they are asymptomatic.

Surgical removal is the treatment of choice for clinical cases.

Cholecystotomy or choledochotomy enable stone removal, but bile duct patency must be checked and is vital for a successful surgical outcome.

The treatment of choice is cholecystectomy, as secondary changes of inflammation, fibrosis and necrosis of the gallbladder are common, and removing the gallbladder elimiates a potential source of disease and a reservoir for subsequent stone formation.

Bile should be cultured and antibiotic sensitivity testing should be performed to ensure adequate antimicrobial cover.

Cholelithiasis Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Soft Tissue Surgery Q&A 18

References

Pasquini, C. (1999) Tschauner's Guide to Small Animal Clinics Sudz Publishing

Slatter, D. (2002) Textbook of small animal surgery Elsevier Health Sciences

Carlyle, T. (1997) Veterinary pathology Wiley-Blackwell

Merck and Co (2008) Merck Veterinary Manual Merial