Necrotizing Cholecystitis

A gallbladder mucocele refers to abnormal enlargement of the gallbladder caused by excessive accumulation of mucus.

Reduced bile flow, impaired gallbladder contractions, and altered water absorption from the gallbladder lumen can promote the formation of biliary sludge. While biliary sludge may contribute to mucocele formation, it is now considered only one component of a multifactorial disease process. This process likely includes inflammation of the gallbladder wall and structural changes in the gallbladder lining that alter the nature of bile and mucus secretion.

Excessive mucus production leads to the buildup of thick, gelatin-like bile inside the gallbladder. Over weeks to months, this increasingly viscous material can completely fill the gallbladder and may extend into the bile ducts. The trigger for this mucus overproduction is not fully understood and is thought to be multifactorial. Conditions that have been associated with gallbladder mucoceles include:

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

Genetic predisposition may also play a role. Shetland Sheepdogs, in particular, have been shown to have an increased risk of gallbladder disease.

Clinical signs are often nonspecific and may be subtle. In some cases, gallbladder mucoceles are discovered incidentally during imaging for unrelated problems. When present, signs may include:

• reduced appetite or anorexia
• lethargy
• vomiting
• diarrhea
• yellow discoloration of the skin or gums (jaundice)
• abdominal pain or abdominal guarding (“splinting”)

Diagnosis relies on a combination of physical examination, blood tests, and diagnostic imaging, with abdominal ultrasound being the most important tool. Ultrasound is particularly valuable in the early stages of disease and should be considered in any animal presenting with gastrointestinal signs.

Early detection is critical. Up to 50% of pets with gallbladder mucoceles may already have a ruptured gallbladder at the time of diagnosis. This percentage can be significantly reduced with prompt imaging and intervention.

As the gelatinous material accumulates, it may cause obstruction of the bile duct, which can be life-threatening. In addition, inflammation of the gallbladder wall can progress to rupture, allowing bile to leak into the abdominal cavity and resulting in bile peritonitis.

In most cases, a proactive surgical approach is recommended.

Pets diagnosed with an incidental mucocele or a “pre-mucocele” on ultrasound should be considered for cholecystectomy (surgical removal of the gallbladder). Historically, some clinicians favored medical management with surgery reserved for patients that deteriorated or developed gallbladder rupture. However, this “wait-and-see” approach increases the risk of sudden, life-threatening rupture.

As a result, many veterinary surgeons now recommend early gallbladder removal, either at initial diagnosis or when a mucocele is identified incidentally on ultrasound. Both open and laparoscopic cholecystectomy in clinically stable patients have been associated with excellent outcomes and rapid return to normal function.

As with any surgery, general anesthesia carries risk. Preoperative bloodwork, imaging, and correction of fluid or electrolyte abnormalities help reduce anesthetic complications. Some patients require intensive care before and after surgery. Biliary surgery also carries inherent risks, including bleeding and bile leakage, which may lead to peritonitis. In such cases, abdominal drains may be required.

After surgery, pets should be kept strictly rested for approximately two weeks, avoiding running, jumping, stairs, or off-leash activity. The surgical incision should be checked daily for signs of proper healing. An Elizabethan collar is often recommended to prevent licking or self-trauma.

Pain medications and, when indicated, treatments for concurrent liver disease or infection are typically prescribed after discharge.

Dogs that undergo cholecystectomy for gallbladder mucoceles and survive the immediate perioperative period generally have an excellent long-term prognosis. Overall mortality rates reported in the literature range from 20–39%, but early surgical intervention appears to significantly lower this risk.

Removed gallbladders—and often a small liver biopsy—are commonly submitted for histopathology and bacterial culture. These results guide postoperative management and help address any underlying liver disease or infection.