Equine viral arteritis


Equine viral arteritis is category 1 restricted matter.

Under Queensland legislation, if you suspect the presence of this disease in any species of animal, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Hotline on 1800 675 888.

Equine viral arteritis (EVA) is an acute, contagious, viral disease of horses and other equids. The virus causes damage to the smaller blood vessels resulting in oedema and haemorrhage in many tissues and organs. Some strains of the virus cause abortion and death in young foals.


A. Arterivirus


Although EVA virus occurs in Australia, disease associated with EVA virus infection has never been recorded here, which suggests that the strains of virus circulating in Australia are of low virulence.

The virus is present in horse populations in many countries throughout the world.


Horses, donkeys

Life cycle

The incubation period is 3 to 14 days.

Affected animals

  • horses

Clinical signs

Exposure to EVA virus may not always result in clinical disease.

When clinical signs occur, they are characterised by:

  • fever
  • depression
  • respiratory symptoms including nasal discharge
  • swelling of the legs especially the hind legs
  • conjunctivitis.

How it is spread

Transmission of EVA infection can occur by respiratory, venereal, congenital, or indirect means. Outbreaks of EVA are usually linked to the movement of animals or the shipment of semen. Viral transmission can be widespread at racetracks or on breeding farms.

Carrier stallions are viral reservoirs and are primarily responsible for persistence of the virus in different horse populations throughout the world.

Monitoring and action

A veterinarian will collect blood samples, and nasopharyngeal and conjunctival swabs for virus isolation and the detection of antibodies.Horse semen should be tested and shown to be free of the disease.


There is no specific treatment and most affected horses recover completely. Treatment for stallions may be advisable to avoid short-term reduced fertility.

Most prevention and control programs are focused on preventing or curtailing dissemination of equine arteritis virus in breeding populations, to minimise the risk of virus-related abortion or death in young foals, and establishment of the carrier state in stallions.