JPC SYSTEMIC PATHOLOGY
REPRODUCTIVE SYSTEM
January 2019
R-V01

Signalment (JPC #1761490):  Equine fetus

HISTORY:  This 5-day-old male Quarterhorse became depressed, weak, and stopped nursing by 36 hours of age.  His condition progressively worsened and he presented to the veterinarian at 48 hours of age.  Bloodwork revealed severe leukopenia, azotemia, hypoproteinemia, severe dehydration, hypoxemia, hypercapnia, and acidosis, then he developed thrombocytopenia.  His condition continued to worsen despite medical therapy, he broke with severe diarrhea, and then died.

HISTOPATHOLOGIC DESCRIPTION:  Lung:  The pleura and interlobular septa are multifocally and moderately expanded by acute hemorrhage and edema.  Within these areas, and scattered throughout the remainder of the section, small vessel walls are expanded mildly by extravasated protein, erythrocytes, and small amounts of cellular debris (vasculitis).  Multifocally, endothelial nuclei rarely are expanded by a single, 2-4um, eosinophilic viral inclusion that peripheralizes the chromatin.  Diffusely, alveolar septa are expanded by congestion, edema, hypertrophic endothelium, few macrophages, few degenerate neutrophils, and occasional cellular debris (necrosis).  Alveolar lumina contain low numbers of alveolar macrophages, degenerate neutrophils, and small to moderate amounts of fibrin.  Bronchiolar epithelium is autolytic, sloughed into the lumen in sheets.

Liver:  Multifocally, there are random small foci of hepatocellular necrosis and loss that are infiltrated by low numbers of histiocytes and admixed with moderate hemorrhage replacing disrupted hepatic sinusoids.  Within these areas, hepatocytes are shrunken and fragmented with hypereosinophilic cytoplasm and karyorrhexis (necrosis).  Rarely, there are multinucleated hepatocytes (viral syncytia).  Within and at the periphery of necrotic, hepatocytes occasionally contain a single, 2-4um, eosinophilic, intranuclear viral inclusion that peripheralizes the chromatin.  There are low numbers of periportal lymphocytes.  There is mild periportal and capsular edema.

Adrenal gland:  Within the cortex, predominantly within the zona reticularis and zona fasciculata, there are multifocal to coalescing areas of lytic necrosis characterized by loss of architecture with replacement by cellular and karyorrhectic debris admixed with abundant hemorrhage, fibrin, edema, and low numbers of degenerate neutrophils.  In these foci, cortical cells are shrunken with hypereosinophilic cytoplasm and pyknotic or karyorrhectic nuclei.  Scattered throughout and at the periphery of necrotic foci, cortical cells contain a single intranuclear, 2-4um, eosinophilic viral inclusion that peripheralizes the chromatin.  There are rare multinucleated viral syncytia with intranuclear viral inclusions as previously described.

MORPHOLOGIC DIAGNOSIS: 

  1. Adrenal gland, cortex:  Adrenalitis, necrohemorrhagic, multifocal to coalescing, severe, with intranuclear viral inclusion bodies, Quarterhorse, equine.
  2. Liver: Hepatitis, necrotizing, multifocal and random, marked, with intranuclear viral inclusion bodies.
  3. Lung: Pneumonia, interstitial, necrotizing, diffuse, mild, with mild vasculitis and rare intranuclear viral inclusion bodies.

ETIOLOGIC DIAGNOSIS:  Herpesviral pneumonia, hepatitis, and adrenalitis

CAUSE:  Equine Herpesvirus-1 (EHV-1)

CONDITION:  Equine Viral Abortion

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

Equine Abortion: 

Viral:

Bacterial:

Fungal:  Late gestation

Non-infectious:

Unknown:

Neonatal Equine Pneumonia: 

Bacterial:

Viral:

Fungal:

COMPARATIVE PATHOLOGY:

Other Significant Alphaherpesviruses:

REFERENCES:

  1. Caswell JL, Williams KJ. The respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmers Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Saunders Elsevier; 2016:568.
  2. El-Nahass E, El-Habashi N, El-Dakhly KM, Tsuchiya Y, Yanai T. Effect of mouse strain on equine herpesvirus-9 infection.  Jour Comp Pathol.  2017;157(1):67-74.
  3. Foster RA. Female reproductive system and mammae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2016: 1175, 1177.
  4. Moeller RB Jr, Crossley B, Pipkin A, Li Y, Balasuriya UBR. Systemic equid alphaherpesvirus 9 in a Grant’s zebra.  Jour Vet Diagn Invest.  2018;30(4):580-583.
  5. Roels E, Dourcy M, Holopainen S, et. al. No evidence of herpesvirus infection in West Highland white terriers with canine idiopathic pulmonary fibrosis.  Vet Pathol.  2016;53(6):1210-1212.
  6. Rosol TJ, Gröne A. Endocrine glands.  In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:340.
  7. Sakaguchi K, Kim K, Langohr I, et. al. Zebra-born neurotropic equid herpesvirus 1 meningoencephalitis in a Thomson’s gazelle (Eudorcas thomsonii).  J Vet Diagn Invest.  2017;29(4):548-556.
  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. Philadelphia, PA: Elsevier Saunders; 2016:399, 432, 435-437.
  9. Valli VEO, Kiupel M, Bienzle D. Hematopoietic system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:145-146, 182-183.


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