Valley Veterinary Hospital

437 Danbury Road
New Milford, CT 06776


Biliary Mucocoele: A Surgical Liver Disease of Dogs

It all starts with a sick, usually middle-aged or older dog. He is listless, not eating, maybe has vomiting and/or diarrhea, fever. These are symptoms that could mean any number of things but usually when he reaches the veterinarian’s examination table he has jaundice (yellow pigmentation visible in the whites of his eyes and possibly on his skin and gums). Hospitalization is recommended to rehydrate him and provide supportive care and blood tests point to a liver problem. Medications are given to minimize the liver’s workload but soon ultrasound is being discussed to image the liver; costs may be rising quickly.

In a survey of dogs with hepatobiliary mucoceles, the following symptoms were observed:

Vomiting – 77%
Lethargy – 73%
Appetite loss – 71%
Jaundice – 47%
Abdominal pain – 44%
Diarrhea – 29%
Fever – 22%


The alphabet soup of blood tests can be confusing and it can be tempting to wait a few days and see how medical support works out before imaging. While this may be a fair choice depending on the patient, there is an important reason to image the liver quickly and this reason is the possibility that surgery is needed urgently.

If the patient has a surgical disease, he will not get better until surgery is performed.

Furthermore, it is possible that a surgical emergency is afoot (not only will surgery be needed but it will be needed immediately).

The sooner the need for surgery is identified, the better the chance of survival.

Why do we need Ultrasound if we Already Know the Problem is Liver Disease?

While blood testing can point to the liver, the fact is that there are numerous diseases that can affect the liver. The liver can have an infection, cancer, scarring (cirrhosis), or any number of conditions. The more specific our diagnosis gets, the more specific treatment can be.

Urinary Bladder Ultrasound

Ultrasound is a non-invasive way to evaluate the internal texture of the liver and gall bladder. By looking at the liver’s texture, it is possible to see a tumor and determine if removing it is possible or if it has invaded too far. Ultrasound can evaluate scarring and abscesses. Through ultrasound it is possible to guide a biopsy needle to an exact area to sample tissue should this be deemed necessary.

Ultrasound evaluates the gall bladder and bile ducts. One of the more important diseases to rule out promptly is biliary mucocoele because it is commonly a surgical emergency. If you wait a few days to see how the patient responds to general liver support, it may be too late to have surgery.

What are the Gall Bladder and Biliary System?

The liver serves as a toxic waste processing center for the body. It filters bacterial products (as well as nutrients) entering the body from the gastrointestinal tract and it removes toxic waste products from the bloodstream. This material that the body would like to get rid of is bound to biochemicals called bile acids. The solution of bile acids, water, mucus, pigments, and cholesterol forms the greenish yellow fluid we call bile.

Bile is made in the liver, then collected into small ducts called bile ductules and bile ducts. The bile is then moved into the greenish round organ called the gall bladder for storage. During food digestion, hormones cause the gall bladder to contract and squirt bile through the large common bile duct and into the intestine. The bile assists with digestion and carries toxins out of the body so they may be eliminated in feces. The gall bladder and its ducts represent the biliary system.


What is a Biliary Mucocoele?

We mentioned that one of the components of bile is mucus. Normal bile is probably less than 3% mucus but when a mucocoele develops, the bile becomes mostly mucus. Normal bile is liquid but mucocele bile is thick and goopy and will not flow easily through the common bile duct. The gall bladder distends trying to pass the mucocele bile and if it actually ruptures, it is likely the patient will likely die.

The gall bladder with a mucocoele develops an appearance on ultrasound described as resembling the cut surface of a kiwi fruit. In this situation, the gall bladder should be removed as soon as possible.

Why Does this Happen?

Mucocoele development starts when the glands that normally supply the gall bladder with mucus become overgrown and overactive. There seems to be an association with this phenomenon and pancreatitis (inflammation of the pancreas) as well as with Cushing's disease (an adrenal hormone excess) but these are not definitive causes and the true relationship these conditions have with mucocoele development is still being worked out. After the liver crisis is resolved, screening for these other conditions may be prudent.

Having Cushing’s Syndrome increases a dog’s risk of developing a biliary mucocoele by 29 times.

Oddly, the biliary mucocoele, which is now a fairly common cause of canine liver disease, was only rarely seen before the 1990s. No one knows why this might be so.

The Shetland sheepdog, cocker spaniel, miniature schnauzer and dachshund seem predisposed to developing biliary mucoceles.

Removing the Gall Bladder (Cholecystectomy)

Removing a dog’s gall bladder is a serious surgery that not all veterinarians are comfortable performing. Discuss with your veterinarian whether referral to a specialist would be best for you and your pet.

The goal is to remove the gall bladder before it ruptures. If it has already ruptured, tissue damaged by the rupture must be cleansed or removed. If the mucocoele has become infected, ruptured, and has spilled infected bile into the abdomen, this is a particularly disastrous outcome but statistically the survival rate is not impacted by this.

Mortality (death) rate with mucocoele surgery is approximately 20-25%.

The gall bladder’s function is mainly one of bile storage. Without the gall bladder, bile simply dribbles into the intestine constantly rather than in controlled squirts. You might think this would be a problem but it turns out not to be. Some patients require long-term medication for liver support but generally speaking, if the dog recovers from surgery prognosis is excellent and the patient can return to normal life.

What if Surgery is not an Option?

There is no question that surgery is the best treatment choice but there is more to the story. Biliary mucoceles can be in an incidental finding in dogs who are not sick or who are sick from something else and are having ultrasound for some other reason. In a patient that is not experiencing problems with a mucocoele, medication may be able to stave off illness.

As for skipping surgery in a dog that is sick from its mucocoele, this is a risky move but survival is possible.

It is possible to attempt treatment with general liver support medications, a low-fat diet, and choleretics (medications to help liquefy bile, such as Actigall) but the problem is that the gall bladder is obstructed with a big wad of goop. This goop is unlikely to liquefy in a timely fashion if at all no matter what we do.