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Basics ⬇

Outline

OVERVIEW

Discrete hepatic abscesses are uncommon but ascending septic cholangiohepatitis is common in the horse.

Signalment!!navigator!!

  • Cholangiohepatitis is most commonly diagnosed in adult horses without additional age or sex predilection
  • Focal abscesses are sporadic and may rarely affect foals, e.g. Rhodococcus, umbilical vein infection, or an adult horse, e.g. tumor necrosis

Signs!!navigator!!

  • The signs of cholangiohepatitis may include weight loss, icterus, abdominal pain, fever, and dermatitis
  • In severe cases, there may be fulminant hepatic failure evidenced by encephalopathy and photosensitization
  • Focal hepatic abscesses may cause ill thrift and sometimes colic

Causes!!navigator!!

  • Cholangiohepatitis—thought to be the result of ascending infection from enteric Gram-negative bacteria. There is generally no historical intestinal disease to explain the ascending infection. The inflammation of the bile epithelium and enzymes released from the bacteria may cause calcium bilirubinate calculi to form
  • Discrete abscesses—may occur, although rarely, from intestinal–hepatic adhesions with necrosis, parasite migration, Corynebacterium pseudotuberculosis-, Rhodococcus-, or Streptococcus-disseminated infections in younger horses, neoplastic abscessation, septic portal vein thrombosis, extension of an umbilical vein abscess into the liver, or as a result of local vascular compromise (from hepatic lobe torsion or hepatic vessel thrombosis) leading to a focal region of tissue hypoxia and liver lobe necrosis. Infectious necrotic hepatitis (Clostridium novyi or Black disease) will also result in hepatic abscessation or necrosis

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • The differential diagnosis for chronic colic is extensive. However, the differential diagnosis for colic with marked jaundice and moderately to markedly elevated liver enzymes includes cholangiohepatitis, right dorsal displacement of the large colon, and neoplasia
  • Fever, leukocytosis, and elevated serum globulin, in addition to the above, would be nearly pathognomonic for cholangiohepatitis

CBC/Biochemistry/Urinalysis!!navigator!!

  • Serum laboratory abnormalities in horses with cholangiohepatitis include marked elevations in GGT (generally >300 U/L), less marked elevation in hepatocellular enzymes, elevations in conjugated bilirubin (which may, on a few occasions, approach ≥50% of the total bilirubin), increased serum bile acids, and elevated serum globulins
  • CBC generally reveals a mature neutrophilia with mild elevation in plasma fibrinogen
  • Foals and horses with discrete hepatic abscess(es) may have mild elevations only in GGT without increases in hepatocellular enzymes or bilirubin
  • Neutrophil counts in peripheral blood are generally increased and may be dramatic with Rhodococcus equi abscess(es)
  • Blood fibrinogen and globulins are generally increased with any abscess, although they may not be abnormal with neoplasia-related abscess and R. equi

Imaging!!navigator!!

  • US examination of the liver (both right and left side) is the imaging procedure of choice. Only a small percentage of the liver can be visualized on abdominal US in the adult; a greater percentage can be visualized in the foal
  • Cholangitis may cause distended bile ducts (in ≈60% of cases), calculi with acoustic shadowing, sludge with acoustic enhancement, and a subjective hepatomegaly
  • In acute cases, hepatomegaly may be present, whereas in more longstanding cases increased echogenicity (fibrosis) may be apparent
  • In horses or foals with focal abscesses, the echogenicity of the abscess is variable
  • CT can be used to image the liver in foals if discrete lesions are suspected

Other Diagnostic Procedures!!navigator!!

  • The most important invasive diagnostic procedure is needle aspirate and/or biopsy for aerobic/anaerobic culture and sensitivity and microscopic examination of the liver
  • This can be safely performed using a biopsy needle after outlining the location of the liver via US
  • If obstruction of the common bile duct is suspected, duodenal endoscopy may allow visualization of the stone or a large bulge at the opening of the duct

Treatment ⬆ ⬇

TREATMENT

  • Hospitalization may not be required unless IV fluids are needed
  • Antimicrobials are the mainstay of treatment, with surgery as a secondary option to remove obstructing calculi if not responsive to medical therapy
  • If a focal hepatic abscess is in a surgically accessible area and medical management is not yielding results, then rib resection can be performed to facilitate surgical intervention and draining
  • Icteric horses should not be exposed to sunlight until bilirubin has returned to a normal range
  • Since hepatoencephalopathy rarely occurs, a normal diet can be fed

Medications ⬆ ⬇

MEDICATIONS

Drugs and Fluids

  • The primary treatment for septic cholangiohepatitis is long-term, appropriate treatment with antibiotics (based upon culture and sensitivity). Several drugs have been used successfully in treating the condition. These include appropriate combinations of trimethoprim–sulfa (30 mg/kg every 12 h) (>50% of the organisms may be resistant), enrofloxacin (7.5 mg/kg every 24 h), metronidazole (15 mg/kg every 8-12 h), ceftiofur sodium (3 mg/kg every 12 h), gentamicin (6.6 mg/kg every 24 h), and sodium penicillin IV (20,000 U/kg every 6 h) or procaine penicillin IM (25,000 U/kg every 12 h). Antimicrobials that can be given PO are preferred since long-term treatment (3 weeks to 6 months) is generally required. If culture and sensitivity cannot be performed or is inconclusive then empirical antibiotic therapy may have to be instituted and changed based on clinical response
  • Parenterally administered antibiotics, fluids, pentoxifylline, and DMSO may be required for some cases with severe anorexia, biliary sludge, and persistent fevers
  • NSAID treatment (e.g. flunixin meglumine) should be used at routine dosages for abdominal pain and during the first 3–5 days of antimicrobial therapy
  • Horses with marked hepatic fibrosis have a poor prognosis and are not surgical candidates
  • Discrete or focal abscess(es) should be treated with appropriate antibiotics based upon culture and sensitivity of aspirated fluid or knowledge of suspected pathogen
  • Large abscess(es) or infected umbilical veins should be drained or removed

Follow-up ⬆ ⬇

FOLLOW-UP

  • Clinical improvement is seen before normalization of GGT; it is recommended to continue antimicrobial therapy until the GGT has returned to normal range or at least <100 U/L
  • After discontinuing antimicrobials, a follow-up measurement of GGT should be performed
  • In cases of hepatic abscesses, follow-up with US is recommended for monitoring

Expected Course and Prognosis

The prognosis of septic suppurative cholangitis is good with medical therapy if no obstructing calculi are found and echogenicity of the liver is normal. Horses with GGT >2500 U/L have recovered.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Abbreviations!!navigator!!

Suggested Reading ⬆ ⬇

Cypher EE, Kendall AT, Panizzi L, et al. Medical and surgical management of an intra-abdominal abscess of hepatic origin in a horse. J Am Vet Med Assoc 2015;247(1):98–105.

Divers TJ. The equine liver in health and disease. Proc Am Assoc Equine Pract 2015;61:66–103.

Johnston JK, Divers TJ, Reef VB, Acland H. Cholelithiasis in horses: ten cases (1982-1986). J Am Vet Med Assoc 1989;194:405–409.

Peek SF. Cholangiohepatitis in the mature horse. Equine Vet Educ 2004;16(2):72–75.

Peek SF, Divers TJ. Medical treatment of cholangiohepatitis and cholelithiasis in mature horses: 9 cases (1991-1998). Equine Vet J 2000;32(4):301–306.

Author(s) ⬆

Authors: Thomas J. Divers and Nikhita P. De Bernardis

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa