Feline Acute Neutrophilic Cholangitis (Suppurative Cholangiohepatitis)

1. Definition

Acute neutrophilic cholangitis is an inflammatory hepatobiliary disorder in cats characterized by neutrophilic infiltration of the intrahepatic bile ducts and portal areas. This condition often results from ascending bacterial infections originating from the gastrointestinal tract.

2. Species Commonly Affected

Domestic cats, particularly middle-aged to older individuals.
Breeds with predispositions include Siamese and Persian cats.

3. Etiology

Primary Cause: Ascending bacterial infection from the gastrointestinal tract.
Common Bacterial Isolates:
- Escherichia coli
- Enterococcus spp.
- Clostridium spp.
- Streptococcus spp.
- Bacteroides spp.
Predisposing Factors:
- Anatomical proximity of the feline common bile duct and pancreatic duct, facilitating bacterial migration.
- Concurrent gastrointestinal diseases, such as inflammatory bowel disease or pancreatitis.

4. Detailed Pathophysiology

In cats, the common bile duct and pancreatic duct often merge before entering the duodenum. This anatomical configuration allows for the potential retrograde movement of bacteria from the small intestine into the biliary system.

Once bacteria ascend into the biliary tract, they incite an acute inflammatory response characterized by:

Neutrophilic Infiltration: Neutrophils migrate into the bile ducts and surrounding hepatic tissue, leading to cholangitis and potentially cholangiohepatitis if hepatic parenchyma is involved.
Bile Duct Obstruction: Inflammation and edema can obstruct bile flow, resulting in cholestasis and hepatocellular injury.
Hepatocellular Damage: Prolonged inflammation may lead to hepatocyte necrosis, fibrosis, and, in chronic cases, cirrhosis.

5. Clinical Signs

Lethargy
Anorexia
Vomiting
Weight loss
Icterus (jaundice)
Fever
Abdominal discomfort or pain
Dehydration

6. Diagnostic Methods

Laboratory Tests:
- Complete Blood Count (CBC): Leukocytosis with a left shift, neutrophilia.
- Serum Biochemistry:
  - Elevated liver enzymes: ALT, AST, ALP, GGT.
  - Hyperbilirubinemia.
  - Elevated bile acids.
Imaging:
- Abdominal Ultrasound:
  - Enlarged, hyperechoic liver.
  - Dilated bile ducts.
  - Gallbladder abnormalities (e.g., sludge, wall thickening).
Definitive Diagnosis:
- Liver Biopsy:
  - Histopathology revealing neutrophilic infiltration of bile ducts and portal areas.
  - Culture and sensitivity testing of bile or liver tissue to identify causative bacteria.

7. Treatment Options

Medical Management:

Antimicrobial Therapy:
- Empirical broad-spectrum antibiotics targeting gram-negative and anaerobic bacteria:
  - Ampicillin: 20 mg/kg IV every 8 hours.
  - Enrofloxacin: 5 mg/kg IV or PO once daily.
  - Metronidazole: 10–15 mg/kg PO every 12 hours.
- Adjust antibiotics based on culture and sensitivity results.
Supportive Care:
- Fluid Therapy: Correct dehydration and electrolyte imbalances.
- Nutritional Support: High-quality, easily digestible diet; consider feeding tube placement if anorexia persists.
- Hepatoprotective Agents:
  - S-Adenosylmethionine (SAMe): 20 mg/kg PO once daily.
  - Vitamin E: 10 IU/kg PO once daily.
Choleretic Agents:
- Ursodeoxycholic Acid: 10–15 mg/kg PO once daily; promotes bile flow and has immunomodulatory effects.
Analgesia:
- Buprenorphine: 0.01–0.02 mg/kg IV or transmucosal every 8–12 hours for pain management.

Surgical Intervention:

Indicated in cases with biliary obstruction, gallbladder rupture, or cholelithiasis.
Procedures:
- Cholecystectomy: Surgical removal of the gallbladder.
- Biliary Decompression: Placement of a biliary stent or external drainage.
- Bile Duct Exploration: Removal of obstructive choleliths or debris.
Postoperative Care:
- Continued antimicrobial therapy.
- Monitoring for signs of bile leakage or peritonitis.
- Supportive care as outlined above.

8. Complications / Prognosis

Complications of Feline Acute Neutrophilic Cholangitis (Suppurative Cholangiohepatitis)

Complication	Pathogenesis	Clinical Consequence
Biliary Obstruction	Edema, cellular debris, or choleliths within bile ducts → mechanical blockage	Extrahepatic bile duct obstruction (EHBO) → marked hyperbilirubinemia, icterus, hepatocellular injury
Gallbladder Mucocele or Rupture	Increased gallbladder wall tension from inflammation or infection → rupture	Bile peritonitis → septic shock, severe peritonitis, high mortality
Hepatic Abscess Formation	Persistent localized bacterial infection within hepatic parenchyma	May require surgical drainage; risk of systemic bacteremia
Septicemia / Systemic Inflammatory Response Syndrome (SIRS)	Ascending bacterial infection enters bloodstream	Systemic hypotension, hypoglycemia, DIC, multi-organ dysfunction
Chronic Cholangitis / Fibrosis	Ongoing inflammation promotes fibroblast activation and scarring	Irreversible hepatic fibrosis, biliary cirrhosis, liver failure
Pancreatitis	Shared pancreaticobiliary duct in cats allows concurrent infection	Vomiting, abdominal pain, systemic illness, worsened prognosis
Hepatic Encephalopathy	Hepatic insufficiency leading to ammonia accumulation	Neurologic signs: ptyalism, ataxia, seizures, coma
Coagulopathies	Liver dysfunction impairs production of coagulation factors (esp. II, VII, IX, X)	Spontaneous bleeding, prolonged clotting times (PT, aPTT)
Portal Hypertension	Fibrosis impeding portal blood flow	Ascites, acquired portosystemic shunts, GI bleeding

Prognosis:

Factor	Prognosis Impact
Early diagnosis + aggressive medical management	Favorable to good
Presence of biliary obstruction, rupture, or septic peritonitis	Guarded to poor
Progression to chronic cholangitis or cirrhosis	Poor long-term prognosis
Multi-organ involvement (pancreatitis, IBD)	Complicates management, worsens prognosis

9. Zoonotic Potential

→ None reported

The bacteria involved (E. coli, Clostridium, Enterococcus, etc.) are zoonotic in certain contexts but not through direct transmission of feline cholangitis.
Standard hygiene precautions for veterinary staff when handling bile or infected tissues are recommended.

10. NAVLE-Specific Tips

Most common type of feline cholangitis = Neutrophilic (acute suppurative)
Ascending infection due to unique feline biliary anatomy → shared bile and pancreatic duct in cats.
Common bacteria = E. coli, anaerobes
Treatment = broad-spectrum antibiotics (Ampicillin + Enrofloxacin + Metronidazole)
Do not forget Ursodeoxycholic Acid → increases bile flow
Liver biopsy = gold standard
Complications = EHBO, septic peritonitis, pancreatitis
Remember association with "triaditis" = IBD + Pancreatitis + Cholangitis in cats