Feline Cholangitis and Cholangiohepatitis – NAVLE Study Guide

Overview and Clinical Importance

Feline cholangitis/cholangiohepatitis syndrome (CCHS) is the most common acquired inflammatory liver disease in domestic cats and ranks as the second most common hepatobiliary disorder after hepatic lipidosis. Understanding this condition is essential for the NAVLE, as it frequently appears in board examination questions and has significant clinical implications for feline practice.

Cholangitis refers to inflammation of the biliary ducts, while cholangiohepatitis describes inflammation that has extended into the periportal hepatic parenchyma beyond the limiting plate. The unique feline anatomy, where the common bile duct and major pancreatic duct share a common opening at the major duodenal papilla, predisposes cats to concurrent inflammatory disease affecting the liver, pancreas, and intestines, known as triaditis.

Anatomical Considerations

Unique Feline Hepatobiliary Anatomy

The feline biliary system has several unique anatomical features that predispose cats to hepatobiliary disease. The common bile duct (CBD) is long and tortuous, traveling from the liver through the hepatoduodenal ligament to join the duodenum at the major duodenal papilla, located approximately 3 cm caudal to the pylorus.

Feline vs. Canine Biliary Anatomy Comparison

WSAVA Classification of Feline Cholangitis

The World Small Animal Veterinary Association (WSAVA) Liver Standardization Group established the current classification system, recognizing three distinct forms of feline cholangitis:

Neutrophilic (Suppurative) Cholangitis

Pathophysiology

Neutrophilic cholangitis is the most common form of feline cholangitis. The proposed pathogenesis involves ascending bacterial infection from the gastrointestinal tract through the shared opening at the major duodenal papilla. The sphincter of Oddi normally prevents retrograde bacterial contamination, but dysfunction or inflammation can allow enteric bacteria to colonize the biliary tree.

Escherichia coli is the most commonly isolated organism, either alone or in combination with other enteric bacteria including Enterococcus spp., Enterobacter spp., Streptococcus spp., Clostridium spp., and Bacteroides spp.

Clinical Presentation

Neutrophilic cholangitis typically affects young to middle-aged cats (mean age 5-7 years) and presents with an acute onset of illness, often less than 5 days duration before presentation.

Clinical Signs of Neutrophilic Cholangitis

Laboratory Findings

Lymphocytic (Nonsuppurative) Cholangitis

Pathophysiology

Lymphocytic cholangitis is characterized by infiltration of small lymphocytes (predominantly T-cells) and plasma cells in the portal areas with varying degrees of periductal fibrosis and bile duct proliferation. The etiology remains unknown, but an immune-mediated mechanism is suspected based on the T-cell predominant infiltrate and similarity to human primary sclerosing cholangitis.

This form tends to be slowly progressive and may be clinically silent during its initial stages. Cats are often chronically ill at the time of diagnosis, having been symptomatic for weeks to months. Persian cats and Norwegian Forest Cats may have a breed predisposition.

Clinical Presentation

Lymphocytic cholangitis typically affects middle-aged to older cats with a chronic, insidious onset of clinical signs often lasting weeks to months before presentation.

Clinical Signs of Lymphocytic Cholangitis

Triaditis: Concurrent Organ Inflammation

Triaditis refers to the concurrent presence of cholangitis, pancreatitis, and inflammatory bowel disease (IBD). Studies have shown that up to 83% of cats with cholangiohepatitis have concurrent inflammation of the duodenum and/or jejunum, and approximately 50% have pancreatic lesions.

Diagnostic Approach

Laboratory Diagnostics

Diagnostic Imaging

Abdominal Ultrasound

Abdominal ultrasonography is the imaging modality of choice for evaluating feline hepatobiliary disease. However, it is important to note that up to 58% of cats with triaditis may have no detectable ultrasound abnormalities.

Liver Biopsy

Definitive diagnosis of cholangitis requires histopathologic evaluation of liver tissue. This allows differentiation between neutrophilic and lymphocytic forms and assessment of disease severity.

Biopsy methods include:

• Ultrasound-guided Tru-cut biopsy: Minimally invasive but ~50% discordance with surgical biopsy; smaller sample size may miss focal lesions
• Laparoscopic biopsy: Larger samples; allows visualization of other organs
• Surgical (exploratory laparotomy): Gold standard; allows assessment of all organs, bile culture, and wedge biopsies from multiple lobes

Treatment

Neutrophilic Cholangitis Treatment Protocol

Duration: Antibiotic therapy should continue for a minimum of 4-6 weeks for acute disease and 8-12 weeks for chronic disease or until liver enzymes normalize.

Lymphocytic Cholangitis Treatment Protocol

Liver Fluke-Associated Cholangitis Treatment

Platynosomum spp. liver fluke infestation is found in tropical and subtropical regions (Florida, Hawaii, Puerto Rico, Caribbean, Brazil). Treatment is with praziquantel 20 mg/kg PO q24h for 3-5 consecutive days. This is often curative if diagnosed before extensive hepatic damage has occurred.

Supportive Care

• IV Fluid Therapy: Correct dehydration and electrolyte imbalances
• Nutritional Support: Critical to prevent hepatic lipidosis; consider esophagostomy tube if anorexic for more than 3-5 days
• Antiemetics: Maropitant (Cerenia) 1 mg/kg SQ/PO q24h or ondansetron 0.1-0.5 mg/kg IV/PO q8-12h
• Appetite Stimulants: Mirtazapine 1.88 mg/cat PO q48h
• Gastroprotectants: Omeprazole 1 mg/kg PO q24h if indicated

Prognosis