Gallbladder Mucoceles are an inherited disorder of the liver affecting Cocker Spaniels. A mucocele is a gallbladder that is severely distended by mucus. It can result in inflammation (cholecystitis) and possible rupture of the gallbladder. Affected dogs usually present with vomiting, jaundice, loss of appetite and abdominal pain. If the gallbladder is not removed before rupture, the dog will become very painful and die. Though it is known that dogs inheriting one copy of the causal Mutation are at increased risk for this disease, the presentation of gallbladder mucoceles is variable between dogs and not all dogs inheriting a copy of the mutation will develop the disease. This suggests that there are environmental or other genetic factors responsible for modifying disease expression. Because gallbladder mucoceles have symptoms that are common to other diseases, it can be difficult to diagnosis without ultrasonography or surgery.