A gallbladder mucocele is the distention of the gallbladder by an inappropriate accumulation of mucus.
Decreased bile flow, decreased gallbladder motility, and altered absorption of water from the gallbladder lumen are predisposing factors to biliary sludge. Biliary sludge may be a precipitating factor for the development of canine biliary mucoceles. However, it is more likely to be a small part of a complex disease process involving inflammation of the gallbladder wall and changes to the lining of the gallbladder changing the consistency of its secretions.
Hypersecretion of mucus leads to an accumulation of thick gelatinous bile within the gall bladder. Increased viscosity over a period of weeks or months leads to thick gelatinous material eventually occupying the entire lumen of the gallbladder and in some cases also being present in the ducts. The inciting cause of mucus hypersecretion is likely multifactorial and may be linked to certain diseases, such as:
- Cushing’s disease (hyperadrenocorticism)
- inflammatory bowel disease
Certain genetic predispositions may play a role as Shetland sheepdogs were recently shown to be predisposed to gallbladder disease.
Clinical signs associated with gallbladder mucocele are often nonspecific and vague and, in some cases, a mucocele is discovered incidentally. Your pet may show signs including:
- decreased appetite
- a yellowish tinge to the skin or gums
- abdominal pain or splinting
Diagnosis of the gallbladder mucoceles relies on physical examination by your primary care veterinarian and blood work combined with imaging modalities, like abdominal ultrasound. Abdominal ultrasound is incredibly useful early in the disease process and should be considered in any animal with clinical signs related to gastrointestinal upset (Figure 1). Up to half of pets with gallbladder mucoceles have a gallbladder rupture at the time of diagnosis and this number can be greatly reduced with early diagnostic intervention.
The presence and progression of gelatinous material in the gallbladder may lead to a life threatening obstruction of the bile duct or the inflammatory changes to the wall of the gallbladder can lead to rupture and spillage of bile contents into the abdomen (Figure 2).
Your pet should be kept quiet for two weeks after gallbladder surgery, avoiding running, jumping, playing, stairs, or off-leash activity. The abdominal incision should be monitored for appropriate healing.
Dogs with gallbladder mucoceles that undergo cholecystectomy and survive the immediate perioperative period have an excellent long term prognosis. Overall mortality rates are reported to be between 20-39% for this disease, however, early surgical intervention may significantly reduce mortality rates. The resected gallbladder and a small piece of liver may be submitted for biopsy and bacterial culture by your veterinary surgeon.