JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
August 2018
D-B06

Signalment (AFIP ACCESSION # 87-650):  3-week-old foal

HISTORY:  Found dead.

HISTOPATHOLOGIC DESCRIPTION:  D-B06a:  Liver:  Multifocally and randomly affecting approximately 70% of the hepatic parenchyma, there are numerous, coalescing, up to 1 mm in diameter foci of lytic necrosis and inflammation, characterized by replacement of parenchyma with eosinophilic cellular and karyorrhectic debris, admixed with fibrin, edema, hemorrhage, and few entrapped individualized hepatocytes. These areas are rimmed by large numbers of viable and degenerate neutrophils and fewer macrophages and lymphocytes.  Adjacent hepatocytes are swollen with pale, vacuolated cytoplasm (degeneration), or are shrunken and hypereosinophilic with pyknotic nuclei (necrosis), or have retention of cellular architecture and loss of differential staining (coagulative necrosis).  Peripheral, less affected hepatocytes often contain numerous stacked, pale, basophilic, filamentous (1x 5um) bacilli.  Portal areas and the subcapsular space are expanded up to three times normal by ectatic lymphatic vessels (edema), hemorrhage, fibrin, and low numbers of lymphocytes, plasma cells, macrophages, and rare neutrophils , and have increased bile duct profiles (biliary ductular reaction).

D-B06b:  Liver (Warthin-Starry, pH 4.0): Within hepatocytes at the periphery of necrotic areas are many argyrophilic, filamentous bacilli. Bacilli occur in parallel and perpendicular sheaves and bundles as well as individually.  Occasionally bacilli are free within necrotic debris.

MORPHOLOGIC DIAGNOSIS:  Liver:  Hepatitis, random, suppurative, necrotizing, acute, multifocal to coalescing, severe, with intracellular argyrophilic bacilli, breed not specified, equine.

ETIOLOGIC DIAGNOSIS:  Clostridial hepatitis

CAUSE:  Clostridium piliforme (previously Bacillus piliformis)

SYNONYMS:  Tyzzer's disease

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

For random necrotizing hepatitis in foals:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, Iowa: Blackwell Publishing; 2016: 53-54,137-138, 181-182, 201-203, 225, 275-276.
  2. Cullin JM, Stalker MJ. Liver and biliary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Vol 2. Philadephia, PA: Elseveier; 2016:317-318.
  3. Jenkins JR, Oglesbee BL. Gastrointestinal diseases. In: Carpenter JW, Quesenberry KE, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. St Louis, MO: Elsevier Saunders; 2012:199-200.
  4. Mete A, Eigenheer A, Goodnight A, Woods L. Clostridium piliforme encephalitis in a weaver bird (Ploceus castaneiceps). J Vet Diagn Invest. 2011; 23: 1240-1242.
  5. Neto RT, Uzal FA, Hodzic E, Persiani M, Jolissaint S, et al. Coinfection with Clostridium piliforme and Felid herpesvirus 1 in a kitten. J Vet Diagn Invest. 2015; 27(4):547-51.
  6. Pearson EG. Tyzzer’s Disease in Foals. In: Smith B, ed. Large Animal Internal Medicine. 4th ed. St. Louis, Missouri: Mosby; 2009:902.
  7. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Vol 2. Philadephia, PA: Elseveier; 2016 :99, 113-114, 183-194.
  8. Zachary JF. Mechanisms of microbial infections. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:166-167.


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