Horses Equine Herpes Virus (Rhinopneumonitis)
Equine Herpes Virus (Rhinopneumonitis)
There are several strains of herpes virus that can infect horses, but the most important is the equine herpesvirus 1, which contains the Rhinopneumonitis virus, and has two subtypes.
Rhinopneumonitis subtype 2 was the main cause of herpes induced respiratory disease until 1979 when the virtually unheard of rhinopneumonitis subtype 1 was brought to the UK from the USA.
Outbreaks of this disease spread rapidly through all ages of the UK’S horse population who had little immunity to this subtype.
This resulted in many racing stables, livery yards and riding schools being shut down for many months in the mid-1980s.
Since then, this virus has been the one most frequently isolated in cases of post-viral lethargy syndrome (chronic fatigue syndrome).
Symptoms of the disease
Usually, the cough is less pronounced than in influenza, but the nasal discharge more frequent becomes yellowish/green (purulent) as secondary bacteria become involved.
The horse is dull, off its food, with a temperature of up to 106°F.
A characteristic of this virus infection is that the mandibular lymph nodes at the angle of the cheekbones between the lower jaw are frequently swollen and tender.
In some cases, these may develop into abscesses and rupture. This can lead to the miss-diagnosis of strangles.
Several complications are associated with infection by this virus.
In young foals, pneumonia may develop.
Mares in their last trimester (1/3) of pregnancy may abort.
Some horses develop stiffness of the limbs with some becoming paralyzed, particularly in their hind legs.
Treatment of Equine Herpes Virus (rhinopneumonitis)
This is carried out in much the same way as for influenza.
A vaccine is also available and strongly advised for horses that compete or if they are going to stud.
Like influenza, isolation is important as is attention to hygiene between horses and nursing.