Case AP07-2606Case AP07-2606

Danielle L. Brown Danielle L. Brown NC State University, College of NC State University, College of

Veterinary MedicineVeterinary Medicine

Co-presenters:Co-presenters:Dr. Talmage Brown, Dr. James GuyDr. Talmage Brown, Dr. James Guy

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History and PE FindingsHistory and PE Findings

7-year-old Paint 7-year-old Paint Horse mareHorse mare

Presented for 2 Presented for 2 day history of day history of colic, anorexia, colic, anorexia, and depressionand depression

Normal TPRNormal TPR Rectal examination Rectal examination

within normal within normal limitslimits

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Clinical Pathology Data and Clinical Pathology Data and Case ProgressCase Progress

CBC: Leukopenia with neutropenia and CBC: Leukopenia with neutropenia and lymphopenia, thrombocytopenialymphopenia, thrombocytopenia

Chemistry panel: Elevated liver enzymes Chemistry panel: Elevated liver enzymes (ALP, AST, GGT, Bilirubin), Elevated CK(ALP, AST, GGT, Bilirubin), Elevated CK

Next morning:Next morning: Dyspnea, mucopurulent nasal dischargeDyspnea, mucopurulent nasal discharge Toxic mucous membranesToxic mucous membranes Very uncomfortableVery uncomfortable Laterally recumbentLaterally recumbent

Humanely euthanized and submitted for Humanely euthanized and submitted for necropsynecropsy

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Gross examinationGross examination Moderate subcutaneous edemaModerate subcutaneous edema Intestinal serosal petechiae and ecchymosesIntestinal serosal petechiae and ecchymoses Hepatic blood vessels prominent and congestedHepatic blood vessels prominent and congested Several small strongyles within large colonSeveral small strongyles within large colon Lungs:Lungs:

Failed to collapseFailed to collapse Mottled appearance with coalescing slightly firm white Mottled appearance with coalescing slightly firm white

focifoci

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Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

website only

Presented at SEVPAC 2008 – Permission granted for use on SEVPAC

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Morphologic DiagnosisMorphologic Diagnosis

Liver: Multifocal to coalescing, Liver: Multifocal to coalescing, severe, acute hepatic necrosis with severe, acute hepatic necrosis with intranuclear inclusion bodies and intranuclear inclusion bodies and fibrinoid vascular necrosisfibrinoid vascular necrosis

Etiology: Equine herpesvirus-4 Etiology: Equine herpesvirus-4 isolated from liver and kidneyisolated from liver and kidney

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EHV-1 vs EHV-4EHV-1 vs EHV-4

Show considerable cross-reactivityShow considerable cross-reactivity Until 1981 were considered as subtypes of Until 1981 were considered as subtypes of

same virussame virus Both are endemic in horse populations Both are endemic in horse populations

worldwideworldwide Horses are repeatedly infected by both viruses Horses are repeatedly infected by both viruses

in nature and disease signs become less severe in nature and disease signs become less severe with progressive episodes later in lifewith progressive episodes later in life

Both cause rhinopneumonitisBoth cause rhinopneumonitis EHV-1 is main cause of abortions, paresis, and EHV-1 is main cause of abortions, paresis, and

neonatal foal deathsneonatal foal deathsPresented at SEVPAC 2008 –

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PathogenesisPathogenesis

Mainly transmitted through inhalationMainly transmitted through inhalation Virus first replicates in upper Virus first replicates in upper

respiratory epithelium and local lymph respiratory epithelium and local lymph nodesnodes

Results in leukocyte-associated viremiaResults in leukocyte-associated viremia Virus later replicates within endothelial Virus later replicates within endothelial

cellscells Latency in lymphoid and neural tissues Latency in lymphoid and neural tissues

demonstrated for both virusesdemonstrated for both virusesPresented at SEVPAC 2008 –

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Unusual presentations of equine herpesvirus

infection Neonatal mortality due to EHV-4 in a

foal (O’Keefe et al, 1995) Necrosis and intranuclear inclusions

seen in lung, liver and small intestinal mucosa

PCR detected EHV-4 Disseminated EHV-1 infection in a 2-

year-old filly (Hamir et al, 1994) Random necrosis seen in lung, liver,

spleen, and adrenal glands with numerous intranuclear inclusion bodies

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Acknowledgements

Dr. Talmage Brown Dr. James Guy Sandra Horton and rest of NCSU-

CVM histology laboratory staff Resident mates and senior

pathologists

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Questions?

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References Reed SM and Toribio (2004) Equine herpesvirus 1

and 4. Vet Clin Equine 20:631-642. Hamir AN et al (1994) Disseminated equine

herpesvirus-1 infection in a 2-year-old filly. JVDI 6:493-496.

O’Keefe JS et al (1995) Neonatal mortality due to equid herpesvirus 4 (EHV-4) in a foal. Aust Vet J 72:353-354.

Patel JR and Heldens J (2005) Equine herpesviruses 1 (EHV-1) and 4 (EHV-4) – epidemiology, disease and immunoprophylaxis: a brief review. Vet J 170:14-23.

van Maanen C (2002) Equine herpesvirus 1 and 4 infections: an update. Vet Q 24:58-78.

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