Cholangiocellular Carcinoma in Dogs
Bile duct carcinoma is a malignant cancer that typically arises from the the epithelia, the cellular lining of the hepatic (liver) bile ducts. This cancer occurs more often in the intrahepatic bile ducts (within the liver) rather than in the extrahepatic bile ducts (outside the liver). In dogs, they are more likely to be found in the left lobe of the liver. Complications of this disease include a failure of the bile to pass through the bile ducts due to the mass that is blocking the duct.
Bile duct carcinomas are aggressive, with metastasis occurring in 67 to 88 percent of affected dogs and they are difficult to completely remove by surgical means. Bile duct carcinomas commonly metastasize to the lungs, lymph nodes of the liver, and peritoneum (abdominal lining).
Because of carcinoma's tendency to metastasize widely, it can also spread to other regional lymph nodes, like the diaphragm (the thin muscular wall dividing the chest cavity from the abdominal cavity), intestines, pancreas, spleen, kidneys, urinary bladder, and the bone. This is classified as a particularly malignant form of cancer, therefore, animals with this disease usually have a guarded to poor prognosis.
This is the second most common type of liver cancer that is found to affect dogs. While its incidence does not appear to be related to breed, it has been found to be more common in female dogs, and in dogs that are ten years of age or older.
Symptoms and Types
Often, dogs with bile duct cancer will have a round or swollen abdomen, which can be due to an enlarged liver or fluid in the abdomen. Other common symptoms associated with the disease include:
- Lack of appetite
- Lack of energy
- Excess need to urinate and drink
- Yellow-skin and/or yellow whites of eyes (as a result of bile dysfunction)
- Possibly due to parasitic infestations
- Suspected relation to environmental exposure to carcinogens
Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms that you provide, and possible incidents that might have led to this condition (e.g., exposure to toxins). Following the initial exam, your veterinarian will order a chemical blood profile, complete blood count, urinalysis and an electrolyte panel. From these your veterinarian will check for elevated liver enzymes, the confirmation of which is indicative of an inflamed or damaged liver that has spilled enzymes into the bloodstream. A test for α-Fetoprotein concentration may help to confirm whether the disease is due to cancer, and a coagulation profile will be ordered to test whether your dog's blood is clotting properly.
X-rays to visualize the abdomen and liver will be taken to localize the carcinoma. An abdominal ultrasound will also be needed to observe the texture and size of the liver and surrounding abdominal organs. If your veterinarian suspects cancer, the lungs will need to be examined using X-ray imaging. This type if cancer has a high rate of metastasis, commonly affecting the lungs and lymph nodes.
If cancer is suspected, it will be necessary for your veterinarian to perform a liver biopsy in order to confirm it. The sample can often be taken by fine needle aspiration, but in some circumstances, a doctor may need a larger tissue sample and will need to perform a simple surgery to collect it. This can be done using a laparoscope, a tubular diagnostic tool that is equipped with a camera and forceps for collecting tissue, and which is inserted through a small surgical incision in the abdominal cavity. The tissue sample will then be sent for laboratory analysis.
Similarly, if your dog has fluid in its abdomen, your veterinarian will draw some out to be sent to the lab for analysis. Pending the results of these tests, your veterinarian will treat the symptoms as necessary.