JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
October 2018
D-P21

Signalment (JPC #2550496):  Hare

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Liver:  Effacing and replacing approximately 70% of the section of liver and compressing adjacent hepatocytes are multifocal to coalescing granulomas composed of a central area of eosinophilic cellular and karyorrhectic debris (lytic necrosis) admixed with numerous aphasmid nematode eggs which are 40 x 60 µm, have a 10-15 µm thick shell with radial striations and variably visible bipolar opercula. Eggs contain either a eosinophilic 15um diameter morula or small amounts of granular eosinophilic debris.   Central areas of necrosis are bounded by numerous degenerate neutrophils, epithelioid macrophages and multinucleated giant cells (foreign body and Langhans type) that are up to 200 µm in diameter and contain up to 40 nuclei; few contain a phagocytized nematode egg.  Surrounding these areas are concentric layers of numerous fibroblasts, eosinophils, fewer lymphocytes and plasma cells and fibrous connective tissue (fibrosis) with many entrapped bile ductules.  Adjacent hepatocytes are multifocally atrophied, occasionally degenerate (swollen and microvacuolated), or rarely necrotic (shrunken and hypereosinophilic with pyknosis).  Multifocally there is an increased number of haphazardly arranged bile ducts (hyperplasia) as well as occasional ectatic ducts.  Multifocally there is hemorrhage within the hepatic parenchyma.  Portal areas are infiltrated by low numbers of eosinophils, lymphocytes and plasma cells.

MORPHOLOGIC DIAGNOSIS:  Liver:  Granulomas, eosinophilic, chronic, multifocal to coalescing, moderate with bi-operculate aphasmid nematode eggs, etiology consistent with Capillaria hepatica, hare (Lepus sp.), lagomorph.

Signalment (UFSM-1):  12-year-old intact male mixed breed dog.

HISTORY:  This dog had a 20-day history of ascites, pleural effusion, vomiting, depression and anorexia which was refractory to treatment.  The dog was humanely euthanized and a necropsy was performed.

HISTOPATHOLOGIC DESCRIPTION:  Liver:  Effacing and replacing approximately 50% of the hepatic parenchyma in the section, and often bridging portal areas, are multifocal to coalescing areas of mature fibrous connective tissue (bridging fibrosis) which replace normal hepatic cords and contain numerous aphasmid nematode eggs which are 40 x 60 µm, have a 10-15 µm thick shell with radial striations and variably visible bipolar opercula.  Eggs contain either a eosinophilic 20um diameter morula, a 30um x 10um elongate basophilic larvae or small amounts of granular debris.  Within these areas, there are low numbers of lymphocytes and plasma cells. Remaining, adjacent hepatocytes are occasionally degenerate (swollen and vacuolated) or necrotic (shrunken and hypereosinophilic with pyknosis). Multifocally, vessels and lymphatics in the portal areas are ectatic (edema and congestion).  Diffusely, hepatic sinusoids are congested.

MORPHOLOGIC DIAGNOSIS:  Liver:  Bridging fibrosis, periportal, chronic, multifocal to coalescing, marked, with hepatocyte loss and numerous bi-operculate aphasmid nematode eggs, etiology consistent with Capillaria hepatica, mixed breed dog, canine.

ETIOLOGIC DIAGNOSIS:  Hepatic capillariasis

CAUSE:  Capillaria hepatica (Calodium hepaticum)

GENERAL DISCUSSION:

PATHOGENESIS:

LIFE CYCLE:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th West Sussex, UK: John Wiley & Sons, Inc.; 2016:153, 301.
  2. Berentsen AR, Vogt S, Guzman AN, et al. Capillaria hepatica infection in black rats (Rattus rattus) on Diego Garcia, British Indian Ocean Territory. J Vet Diagn Invest. 2015;27(2):241-244.
  3. Brash ML, Charlton, BR, et al. Boulianne M ed. Avian Disease Manual. 7th Jacksonville, FL: American Association of Avian Pathologists; 2013: 158-159.
  4. Breshears MA and Confer AW. The Urinary Sytem. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:680.
  5. Gardiner CH, Poynton SL. Aphasmids. In: Gardiner CH, Poynton SL, eds. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: Armed Forces Institute of Pathology; 1999:40-43.
  6. Lopez A and Martinson SA. Respiratory, Mediastinum, and Pleurae. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:548.
  7. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier Ltd; 2016:320.


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