B211 - EQUINE VIRAL ARTERITIS

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B211 - EQUINE VIRAL ARTERITIS

Nature of the disease
Equine Viral Arteritis (EVA), or pink eye, is a contagious disease of horse causing systemic disease as well as abortions due to an Arteraviridae
Classification
OIE, List B disease
Susceptible species
Horses
Distribution
EVA seems to be worldwide distributed. Serological evidences have been found in Australia and New Zealand. It has never been reported in Pacific Islands.
Clinical signs
After an incubation period of 1-10 days, the following signs can be seen at different degrees of severity:
  • Fever,
  • Nasal discharge and rhinitis,
  • Conjunctivitis ("Pink eye") with lacrimation and photophobia, sometimes keratitis,
  • Periorbital oedema,
  • Anorexia and depression,
  • Oedema of prepuce, scrotum, brisket, limbs
  • Dyspnoea (associated to lung oedema) and cough
  • Petechia
  • Abdominal pain, diarrhoea, jaundice,
  • Ataxia,
  • Abortions

Most recent infections seem to be mild.

Post-mortem findings 
All lesions are easily related to the pathogenicity of the virus that damages small arteries walls:
  • Oedema all over the body,
  • Congestion and haemorrhages,
  • Infarcts of the spleen,
  • Pleural, peritoneal effusions
Differential diagnosis 
Specimens required for diagnosis
For identification of the virus specimen can include abortion material, nasal or ocular swabs, full blood on EDTA and semen. At post-mortem specimens include lung, spleen and lymph nodes. Techniques include virus isolation, PCR and immunochemistry.

A variety of serological tests are available: neutralisation (prescribed test for international trade), complement fixation (CF), indirect fluorescent antibody, agar gel immunodiffusion and ELISA. 

Transmission
The disease is mainly transmitted by sexual contact and aerosol. Indirect transmission by fomites is possible but rare. Infected stallions selected for breeding and artificial insemination play a major role in the epidemiology.  
Risk of introduction   
The disease could be introduced via importation of infected animals or semen.
Control / vaccines  
Different type of vaccines are available, killed and attenuated. The attenuated vaccine should not be used in pregnant mares, and generally  vaccination should be avoided in free countries.
References
  • Equine Viral Arteritis, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p. 500-502
  • Office International des Epizooties, 2002
  • Office Vétérinaire Fédéral Suisse
  • Equine Viral Arteritis, In Veterinary Medicine, Saunders, Eight ed, 1997, London p. 1040-1042