Gallbladder Mucocele in Dogs

By A Chakrabarti

Gallbladder Mucocele is caused by obstruction of the storage capacity of the gallbladder due to formation of thick, mucoid bile conglomerate inside the gallbladder, and consequent impairment of its functioning. The accumulated biliary sludge may extend the gallbladder resulting in necrotizing cholecystitis.

Gallbladder Mucocele is common among middle aged to older dogs, particularly Shetland sheepdogs, cocker spaniels and miniature schnauzers, and occurs irrespective of sex.

Symptoms

Gallbladder Mucocele may be symptomatic or asymptomatic. The general symptoms are:
• Vomiting
• Anorexia
• Abdominal discomfort
• Polyuria/polypdisia
• Collapse - vasovagal or bile peritonitis

Physically, the dog may manifest general lethargy, abdominal pain, fever, dehydration and jaundice.

Diagnostic and imaging/ultrasound tests associated with other health conditions may reveal the asymptomatic conditions.

Causes and Risk Factors

The most common causes of Gallbladder Mucocele are:
• Lipid metabolism problems, particularly among Shetland sheepdogs and miniature schnauzers - this condition may be inherent in some dogs
• Gallbladder dysmotility (lack of intra-organ movement);
• Cystic hypertrophy of the mucous producing glands of the gallbladder, a common feature among older dogs - this condition may act as a trigger for Gallbladder Mucocele.
• Taking high fat diet, raised cholesterol, hyperthyroidism, and typical or atypical adrenal hyperplasia, glucocorticoid therapy.

Diagnosis

The differential diagnosis of Gallbladder Mucocele may look into the conditions causing dysmotility of the gallbladder and other factors perpetrating bile stasis like neoplasia, pancreatitis, and choleliths etc.

Diagnosis depends on blood biochemistry, hematology, lab tests and imaging studies.

The common observations are:
Biochemistry:
• Analysis of liver enzymes, ALP, GGT, ALT and AST - high liver enzymes indicate illness; sometimes, this may be the only sign of illness in some dogs or may manifest in the acute stage of the disease;
• Increased bilirubin;
• Low Albumin;
• Electrolyte abnormalities with fluid and acid-base disturbances - due to excessive fluid loss from vomiting or triggered by bile peritonitis;
• Prerenal azotemia

Hematology/CBC
• Anemia
• Leukocyte imbalance

Lab tests:
• High triglycerides

Imaging:
• Radiography or ultrasound studies showing liver abnormalities, distended gallbladder and bile duct, gallbladder wall thickening, presence of gas in the liver, and loss of detail in the abdomen due to inflammation of the soft lining of the abdomen (peritonitis).

The common diagnostic procedures are aspiration sampling of fluids withdrawn from adjacent biliary structures or from the abdominal cavity, laparotomy, liver biopsy, bacterial cultures and sensitivity tests and cell examinations.

Treatment

Gallbladder Mucocele treatment depends on the condition of the patient. Outpatients are generally put on anti-inflammatory and liver protecting agents like Ursodeoxycholic acid and S-Adenosylmethionine (SAM-e). Indoor patients are treated according to their condition demonstrated by imaging and ultrasound studies. Patients with higher lipids are restricted fat-rich foods. If bile peritonitis is confirmed, abdominal lavage is recommended. All patients should be put on hydration therapy to correct fluid and electrolyte imbalances.

Other than broad-spectrum antimicrobials, depending on symptoms, the patients are put on antiemetics, antacids, gastroprotectants, Vitamin K1 and antioxidant medications.

Post-treatment, all Gallbladder Mucocele patients must be periodically monitored with biochemistry, hematology and imaging studies to exclude/include various complications like Cholangitis or Cholangiohepatitis, Bile Peritonitis and EHBDO.

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