Biliary Carcinoma

Biliary or bile duct carcinoma (cholangiocellular carcinoma and cholangiocarcinoma) occurs when the lining of the liver bile ducts begins to produce malignant cells. By the time a cat is typically diagnosed with a carcinoma of the bile duct, the rate of widespread metastasis is 67 to 88 percent, according to Pet MD. Biliary carcinoma is the No. 1 type of liver cancer found in cats.

Bile Ducts

The most common location for biliary cancer in a cat is within the liver's bile ducts instead of on the external liver bile ducts. As the malignant tumor grows, it begins to obstruct the cat's bile duct, causing the liver to swell and become tender to the touch. Cancer within a bile duct is not necessarily a primary cancer. Biliary cancer can be a primary tumor that arose from the liver cells or a secondary cancer caused by widespread metastasis from another organ of the body.

Metastasis

Bile duct carcinoma quickly invades the surrounding lymph nodes, peritoneum, lungs, pancreas, bones, bladder and kidney. When the cat exhibits widespread metastasis to a variety of regions, the prognosis is extremely poor.

Symptoms

Cats with primary or secondary biliary carcinoma will exhibit lethargy, lack of appetite, excessive thirst, frequent urination and yellowing of the whites of the eyes. As the cancer advances, vomiting can occur frequently.

Causes

The cause of primary biliary cancer is unknown. Many theories hold that parasites might be to blame. Overexposure to carcinogens during the cat's lifetime also might contribute to the problem.

Diagnosis

The cat's abdomen will often feel hard and swollen to the touch. The cat may exhibit signs of pain when the liver region is palpitated by hand. If a veterinarian suspects liver cancer, an ultrasound or X-rays will be ordered, followed by a needle biopsy. Once biliary cancer is diagnosed, the veterinarian will evaluate whether the cancer is primary or secondary and what other parts of the body might be affected.

Treatment

If the tumor within the bile ducts of the liver is primary, with virtually no spread to other regions of the body, veterinarians often will choose to remove the tumor surgically. Up to 75 percent of the liver can safely be removed. Chemotherapy is rarely used. When widespread metastasis has occurred, the veterinarian will focus on making the cat's remaining time comfortable and pain-free, because treatment won't be effective.