What is Equine Herpes Virus and why vaccinate?

With five subtypes and no cure, the Equine Herpes Virus poses a serious risk to horse properties. As such, the only solution is to limit the virus’ spread. In this article, we discuss the importance of vaccinating your horse against the Equine Herpes Virus.

What is Equine Herpes Virus and why vaccinate?

Equine Herpes Virus-1 (EHV-1) and Equine Herpes Virus-4 (EHV-4) are the most concerning strains of the virus. Highly contagious and able to spread rapidly, EHV-1 and EHV-4 can debilitate any horse property that houses numerous horses in one location.

A viral infection, Equine Herpes Virus isn’t curable and must be contained with strict vaccination and quarantine control. Exacerbated by stress, the virus can re-emerge at any time after remaining dormant in the horse’s body, so management practices that minimize stress are also imperative.

Signs of Equine Herpes Virus

Following an incubation period, which can last between four and 10 days, the most common symptoms of Equine Herpes Virus include:

  • Fever
  • Nasal discharge
  • Enlarged lymph nodes
  • Decreased fitness
  • Anorexia
  • Lethargy
  • Decreased performance
  • Strange gait

Neurological symptoms are also common in cases of EHV-1. These distressing and often deadly symptoms include:

  • Paralysis
  • Uncoordinated movements
  • Seizures
  • Inability to stand
  • Abortions in pregnant mares

Treating Equine Herpes Virus

 Using a nasal swab, your veterinarian will be able to determine the presence and type of Equine Herpes Virus. However, as a virus, there is no known cure without vaccination — it can only be contained to prevent its spread.

Treatment of Equine Herpes Virus usually involves:

  • Strict isolation
  • Antibiotics to fight secondary infections
  • Anti-inflammatories to encourage eating and drinking

However, vaccination will provide your horse with immunity against the Equine Herpes Virus and limit its potential impact on your horse’s property.

Preventing Equine Herpes Virus 

If your horse is unvaccinated against Equine Herpes Virus, you should follow the below schedule to give them the full benefits of immunity:

  • First dose – Equip EHV 1,4

4-6 week interval

  • Second dose – Equip EHV 1,4

6 month interval

  • Bi-annual booster – Equip EHV 1,4

For studs and other horse breeding facilities, vaccination is also paramount to prevent abortions in mares, which can have disastrous consequences during breeding season.

Every mare should be vaccinated against the Equine Herpes Virus and given a booster at five, seven, and nine months of gestation.


  • Dr Louise Cosgrove

    The founder of Exclusively Equine Veterinary Services, Louise is driven to support horses in their recovery from injury or illness. A graduate of the University of Queensland, with international equin...

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