Bile Duct Inflammation in Cats

Inflammation of the bile duct is called cholangitis. When the liver and gallbladder are also involved, the term used is cholangiohepatitis. Bile duct inflammation can be caused by infection, blockages or parasites, and proper treatment will require diagnosis by a veterinarian. Regardless of the cause, bile duct inflammation is considered a medical emergency and requires a trip to the veterinarian as quickly as possible.

Bile ducts are the part of the digestive system whose function is to transport bile from the liver to the gall bladder and on into the intestines. The liver secretes bile, which is a dark brown or greenish fluid that assists in the digestion of food, especially fats. Bile from the liver is stored in the gallbladder until is it needed for digestion. When bile ducts become inflamed or obstructed, bile cannot flow and the cat becomes ill, exhibiting symptoms such as lack of appetite, vomiting, abdominal pain and sometimes jaundice. Because the symptoms of bile duct inflammation resemble some other metabolic diseases, determining the cause of your cat's illness is unlikely to be possible through simple observation.

The symptoms of bile duct inflammation in cats can range from mild to severe depending on the cause and whether or not other organs are involved. Common symptoms include:

• Lack of appetite, or conversely, sudden excessive appetite
• Weight loss
• Vomiting
• Abdominal pain
• Abdominal swelling
• Lethargy
• Fever
• Swollen lymph nodes
• Jaundice (yellowing of mucous membranes)

Bile ducts can become inflamed due to a variety of causes. 

Infection

Whether originating in the bile duct itself or traveling from the liver or gall bladder, an infection in the bile duct can cause inflammation, resulting in tissue irritation and restriction of the bile flow due to swelling. Infections can be bacterial, viral or fungal in nature, and determining the type of infection is necessary in order to ensure proper treatment.

Blockage

Crystallized stones formed from minerals in the body can travel from the gall bladder and block bile ducts. Fibrosis due to severe trauma (such as that from being hit by a car) or previous surgical procedures can also cause blockages. Other causes include intense swelling triggered by acute infection, bile sludge from the liver, tumors and parasites.

Underlying Disease

Several diseases seen in cats can cause cholangitis or cholangiohepatitis, including feline infectious peritonitis (FIP), feline leukemia virus (FeLV), toxoplasmosis, and coccidiosis. 

Disorders of Other Digestive Organs

Problems originating in the liver, bladder, pancreas or intestines can impact the function of bile ducts. Each instance requires evaluation of the related organ to determine the cause.

If your cat is showing symptoms of bile duct inflammation, making a definitive diagnosis begins with you providing a detailed history of your cat's current symptoms along with any past symptoms or health problems. Prior episodes of bladder stones could indicate a recurrence and potential blockage. Previous abdominal surgery, especially any procedures involving the bladder, liver or small intestines might indicate fibrosis or adhesions. Exposure to other cats, especially those who are potentially not vaccinated against FeLV or FIP, should be disclosed.

Keeping in mind the history and list of symptoms, your veterinarian will perform a thorough physical exam that includes taking your cat's temperature, inspecting mucous membranes, palpation of the abdomen to check for swelling or lumps, and feeling lymph nodes. Based on the findings of the initial exam, your veterinarian will likely conduct other diagnostic tests including the following:

• Blood tests
• Urinalysis
• Stool sample
• Abdominal X-ray
• Ultrasound

The blood, urine, and stool samples will be examined for evidence of bilirubin. Bilirubin is one constituent of bile that is normally excreted via urine and stool, but it will become concentrated in the blood if the bile ducts are not functioning properly. High levels of bile in the blood paired with low levels in stool and urine indicate poor function of bile ducts. Excess bilirubin in the blood causes jaundice, hence the inspection of mucous membranes for the telltale yellow discoloration.

X-rays of the abdomen will sometimes help pinpoint the existence and location of bladder stones, but if nothing shows up on the radiographs your veterinarian might perform an ultrasound. The ultrasound will allow for the evaluation of your cat's organs, specifically swelling or thickening of the liver, pancreas or gall bladder.

If the diagnosis remains elusive, your vet may conduct the following additional tests:

• Ultrasound-guided fine needle aspiration
• Ultrasound-guided biopsy

These tests allow your veterinarian to take samples from the bile ducts and affected organs to look for infection or cancer.

One other procedure that is not uncommon if a blockage is suspected is exploratory surgery. Since blockages and tumors need to be removed surgically anyway, this procedure allows your vet to diagnose and treat the problem at the same time.

The treatment of bile duct inflammation depends on the underlying cause.

Surgery

Blockages are most often treated surgically. Blocked bile ducts represent a medical emergency that must be corrected immediately, and surgery is often the best option. If caught early, the potential for recovery is usually high with normal post-surgical care.

Infection

Antibiotics will be prescribed to treat infections, and the full course of medication must be administered both to ensure that the targeted infection is completely removed and that antibiotic resistance does not occur.

Trauma

Inflammation caused by trauma is likely to be treated using anti-inflammatory drugs, often in conjunction with antibiotics. IV fluids to combat dehydration and prevent shock are typical, and hospitalization is likely. Recovery depends on the nature and severity of the trauma.

Underlying Disease

Bile duct inflammation linked to diseases such as FeLV or FIP require that the triggering disease is treated along with the inflammation. 

After treatment, you will need to have your cat examined by your veterinarian periodically to ensure that the inflammation does not recur. Blood, urine and stool tests should be conducted routinely for as long as your vet feels necessary. Periodic ultrasounds are sometimes advised to allow your vet to view any changes in the organs.

Since diet is often a contributing factor in the inflammation of bile ducts, an appropriate high protein, low fat diet will be prescribed, and your cat will likely need to stay on this diet permanently. Ensuring that your cat always has access to fresh, clean water and remains well hydrated will help prevent future occurrences of bladder stones and bile sludge, common causes of bile duct blockages and inflammation.