Equid alphaherpesvirus 3

Equid Alphaherpesvirus 3

Equid alphaherpesvirus 3 (EHV-3) is a virus that primarily affects horses, causing a condition known as equine coital exanthema. This virus is a member of the Herpesviridae family, which includes other equine herpesviruses such as Equid alphaherpesvirus 1 (EHV-1) and Equid alphaherpesvirus 4 (EHV-4). EHV-3 is specifically classified under the genus Varicellovirus.

Virology

EHV-3 is an enveloped virus with a double-stranded DNA genome. It is closely related to other equine herpesviruses but is distinct in its clinical manifestations and epidemiology. The virus primarily targets the epithelial cells of the genital tract, leading to the characteristic lesions associated with equine coital exanthema.

Clinical Signs

Horses infected with EHV-3 typically present with:

• Vesicular and ulcerative lesions on the genitalia.
• Lesions may also appear on the lips and nostrils in some cases.
• Affected horses may exhibit discomfort and reluctance to breed.

The lesions are usually self-limiting and heal within two weeks without scarring. However, the virus can remain latent in the host and may reactivate under stress or immunosuppression.

Transmission

EHV-3 is primarily transmitted through direct contact during breeding. The virus can also be spread via fomites, such as contaminated equipment or handlers' hands. Unlike EHV-1 and EHV-4, EHV-3 is not typically associated with respiratory disease or abortion.

Diagnosis

Diagnosis of EHV-3 infection is based on clinical signs and can be confirmed through laboratory tests such as:

• Polymerase chain reaction (PCR) to detect viral DNA.
• Virus isolation from swabs of lesions.
• Serological tests to detect antibodies against EHV-3.

Treatment and Management

There is no specific antiviral treatment for EHV-3. Management focuses on:

• Providing supportive care to affected horses.
• Isolating infected animals to prevent the spread of the virus.
• Practicing good hygiene and biosecurity measures during breeding.

Prevention

Preventive measures include:

• Quarantining new arrivals to a breeding facility.
• Regular health checks and monitoring for signs of infection.
• Using artificial insemination to reduce direct contact during breeding.

See Also

• Equid alphaherpesvirus 1
• Equid alphaherpesvirus 4
• Herpesviridae

References

• Allen, G. P., & Bryans, J. T. (1986). Molecular epizootiology, pathogenesis, and prophylaxis of equine herpesvirus-1 infections. Progress in Veterinary Microbiology and Immunology, 2, 78-144.
• Lunn, D. P., Davis-Poynter, N., Flaminio, M. J., Horohov, D. W., Osterrieder, N., Pusterla, N., & Townsend, H. G. (2009). Equine herpesvirus-1 consensus statement. Journal of Veterinary Internal Medicine, 23(3), 450-461.