Brachycephalic Breeds

A gallbladder mucocele is a condition characterized by abnormal enlargement of the gallbladder due to the excessive accumulation of mucus within its lumen.

Several factors can predispose to the formation of biliary sludge, including reduced bile flow, impaired gallbladder motility, and altered water absorption from the gallbladder lining. Biliary sludge may contribute to the development of gallbladder mucoceles in dogs; however, it is generally considered only one component of a more complex disease process. This process involves inflammation of the gallbladder wall and structural changes to the gallbladder lining, which alter the consistency and composition of gallbladder secretions.

Excessive mucus production results in the accumulation of thick, gelatinous bile within the gallbladder. Over a period of weeks to months, increasing viscosity causes this dense, jelly-like material to progressively fill the entire gallbladder lumen and, in some cases, extend into the bile ducts. The underlying cause of mucus hypersecretion is likely multifactorial and may be associated with several systemic diseases, including:

• Hyperadrenocorticism (Cushing’s disease)
• Hypothyroidism
• Inflammatory bowel disease

Genetic factors may also play a role, as recent studies have demonstrated a predisposition to gallbladder disease in Shetland Sheepdogs.

Clinical signs associated with gallbladder mucoceles are often vague and nonspecific, and in some cases the condition is identified incidentally during diagnostic imaging performed for unrelated reasons. Affected pets may exhibit one or more of the following signs:

• Decreased appetite
• Complete loss of appetite (anorexia)
• Lethargy
• Vomiting
• Diarrhea
• Yellow discoloration of the skin or gums (jaundice)
• Abdominal discomfort or guarding

Diagnosis of gallbladder mucoceles is based on a combination of physical examination by the primary care veterinarian, blood test results, and diagnostic imaging, most notably abdominal ultrasound. Abdominal ultrasonography is particularly valuable in the early stages of the disease and should be considered in any patient presenting with gastrointestinal signs (Figure 1).

At the time of diagnosis, up to 50% of pets with gallbladder mucoceles may already have experienced gallbladder rupture. Early diagnostic intervention can significantly reduce this risk.

As the gelatinous material accumulates and progresses within the gallbladder, it may cause life-threatening obstruction of the bile duct. Additionally, inflammatory changes affecting the gallbladder wall may lead to rupture, allowing bile to leak into the abdominal cavity (Figure 2).

In most cases, a proactive treatment approach is recommended for pets diagnosed with gallbladder mucoceles. Animals with an incidentally discovered mucocele or a “premucocele” identified on ultrasound should be considered candidates for surgical removal of the gallbladder, a procedure known as cholecystectomy.

A recent trend has been to delay surgical removal until medical management fails, the patient becomes systemically ill, or gallbladder rupture occurs. However, this “wait-and-see” approach may significantly increase the risk of a catastrophic and life-threatening gallbladder rupture. Consequently, many veterinary surgeons now advocate for early gallbladder removal either at the time of initial diagnosis or when a mucocele is found incidentally during abdominal ultrasound.

Both traditional open and laparoscopic cholecystectomy performed in clinically stable patients with gallbladder mucoceles have demonstrated excellent outcomes, with rapid return to normal function reported in multiple cases.

As with any surgical intervention, general anesthesia carries inherent risks. Preoperative blood testing, imaging studies, and correction of fluid and electrolyte imbalances allow the ACVS board-certified veterinary surgeon to minimize anesthetic risk. Some patients may require intensive care support before and after surgery.

Biliary surgery also carries specific risks, including hemorrhage and leakage of bile into the abdominal cavity, which can result in peritonitis. In such cases, placement of abdominal drains may be necessary to manage bile contamination and inflammation.

Following gallbladder surgery, pets should be strictly rested for approximately two weeks. Activities such as running, jumping, playing, stair climbing, and off-leash exercise should be avoided. The surgical incision must be closely monitored to ensure proper healing. An Elizabethan collar is often recommended to prevent licking or self-inflicted trauma. Pain management medications and treatments for concurrent liver disease or infection are commonly prescribed upon discharge.

Dogs diagnosed with gallbladder mucoceles that undergo cholecystectomy and survive the immediate perioperative period generally have an excellent long-term prognosis. Overall mortality rates for this condition have been reported to range from 20% to 39%; however, early surgical intervention may significantly reduce these rates.

The removed gallbladder and a small liver biopsy sample are often submitted for histopathologic examination and bacterial culture. Results from these tests assist the veterinary team in identifying and managing concurrent liver disease or infection.