JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

October 2017

P-V10

 

Signalment (JPC #N93-1 10):  1-day-old thoroughbred foal

HISTORY:  This foal was weak from birth and showed an elevated respiratory rate and effort.  Mucous membranes were hyperemic and icteric.  Supportive care and treatment, including positive pressure ventilation, were pursued without success.  The foal developed pulmonary hemorrhage and edema terminally and died within one day of its birth.

HISTOPATHOLOGIC DESCRIPTION:  Lung:  Multifocally bronchiolar architecture is effaced by abundant necrotic debris and fibrin, and there are multifocal, patchy areas of hemorrhage and consolidation throughout the section.  Diffusely, bronchial and bronchiolar epithelium is often sloughed, lost and/or necrotic with shrunken hypereosinophilic cytoplasm and pyknotic nuclei, or is degenerate with swollen cytoplasm and loss of cilia.  Multi-nucleated viral syncytial cells of the epithelium are frequent.  Epithelial and syncytial multifocally contain 4um eosinophilic intranuclear inclusion bodies that marginate the chromatin.  The bronchiolar submucosa is expanded by necrotic debris, infiltrating neutrophils and macrophages, fibrin, hemorrhage, and  edema. Multifocally, alveolar septa are necrotic and thickened by neutrophils and macrophages and covered by a brightly eosinophilic 7um thick hyaline membrane composed of polymerized fibrin. Fibrin, hemorrhage, and edema with scattered necrotic debris and neutrophils are within alveolar lumina.  The subpleural space, intralobular septa and perivascular areas are markedly expanded up to 500um by abundant hemorrhage, fibrin, and edema and few macrophages, neutrophils, and lymphocytes.

MORPHOLOGIC DIAGNOSIS:  Lung:  Pneumonia, bronchointerstitial, fibrinonecrotic, acute, diffuse, marked, with subpleural hemorrhage, alveolar hyaline membranes, epithelial syncytial cells, and intraepithelial intranuclear viral inclusion bodies, Thoroughbred, equine. 

ETIOLOGIC DIAGNOSIS:  Equine herpesviral pneumonia (in utero infection)

CAUSE:  Equine herpesvirus-1 (EHV-1)

CONDITION: Equine viral rhinopneumonitis

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURE:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

 REFERENCES:

  1. Cantile C, Youssef S. Nervous system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 1. 6th ed. St. Louis, MO: Elsevier; 2016:383-384.
  2. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6th ed. St. Louis, MO: Elsevier; 2016:568.
  3. Del Piero F, Wilkins PA, Timoney PJ, et al. Fatal Nonneurological EHV-1 Infection in a Yearling Filly. Vet Pathol. 2001:38;474–474.
  4. Lopez A, Martinson SA. Respiratory system, mediastinum, and pleurae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 525-526.
  5. Lunn DP, Davis-Poynter N, Flaminio MJBF, et al. Equine herpesvirus-1 consensus statement. J Vet Intern Med. 2009:23;250-61.
  6. MacLachlan NJ, Dubovi EJ, eds. Fenner’s Veterinary Virology. 5th ed. San Diego, CA: Academic Press; 2017:202-204.
  7. Miller AD, Zachary JF, Nervous system. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 877.
  8. Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 3. 6th ed. St. Louis, MO: Elsevier; 2016:435-437.
  9. Zachary JF. Mechanisms of microbial infetions. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 208.

 

 

 


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