Equine Arteritis Virus (EAV) is a highly contagious viral disease that impacts horses worldwide. This infection poses a considerable challenge to the equine industry, affecting horse health and causing significant economic implications. Understanding its nature, transmission, and prevention is important for horse owners and professionals alike.
Understanding Equine Arteritis Virus
Equine Arteritis Virus (EAV) is the causative agent of Equine Viral Arteritis (EVA). The virus belongs to the Arteriviridae family, which consists of small, enveloped viruses with a positive-sense, single-stranded RNA genome. EAV was first identified in 1953 following an outbreak of respiratory disease and abortion on a horse farm in Ohio. While EAV infection is often subclinical, it can also manifest with varied severity depending on factors like the horse’s age, the viral strain, and its overall condition.
Transmission and Clinical Signs
EAV spreads through several pathways, with respiratory secretions being a common route, especially in close contact settings like barns. Infected horses can shed the virus in nasal discharge and through coughing. Another significant mode of transmission is venereal, occurring when mares are bred with persistently infected stallions. Indirect contact through contaminated objects, such as shared buckets, tack, or clothing, is also a potential route of transmission.
The clinical signs of EAV infection can vary widely, from no apparent symptoms to severe illness. After an incubation period typically ranging from 3 to 14 days, with venereal transmission often showing signs in 6 to 8 days, horses may develop a fever up to 41°C (106°F). Other common signs include lethargy, nasal discharge, and conjunctivitis, often referred to as “pink eye”. Swelling around the eyes (periorbital or supraorbital edema), skin rashes (urticaria), and dependent edema affecting the limbs or underside of the abdomen, including the udder in mares or scrotum in stallions, may also be observed. Abortion is a concerning outcome for pregnant mares, occurring at various stages of gestation.
Diagnosis and Management
Diagnosing Equine Viral Arteritis involves identifying the virus or the horse’s immune response. Diagnostic methods typically include virus isolation from samples like nasal swabs or semen, or Polymerase Chain Reaction (PCR) testing, which detects the viral genetic material. Serology, blood tests to detect antibodies, also helps confirm exposure.
There is no specific antiviral treatment available for EVA; management focuses on supportive care. This includes providing affected horses with adequate rest and administering anti-inflammatory medications to reduce fever and swelling. Good nursing care ensures comfort and recovery. Isolating infected horses from susceptible animals prevents further spread.
Prevention and Control
Preventative measures control the spread of Equine Arteritis Virus. Vaccination is a primary strategy, particularly for breeding stallions and mares intended to be bred to carrier stallions. Veterinary guidelines for vaccination schedules and proper administration should be followed for maximum protection. However, vaccines may not be universally licensed in all regions.
Rigorous biosecurity protocols prevent EAV transmission. This includes quarantining all new horses, or those returning from events or sales, for three to four weeks before introducing them to the general population. Strict hygiene practices, especially during the breeding season, are advised, alongside avoiding the sharing of equipment such as brushes, tack, or feeding buckets. Monitoring horse movements, especially those of breeding animals, contributes to disease control.
Impact on Breeding and Movement
Equine Arteritis Virus has significant economic and practical consequences, particularly within the equine breeding sector and for international horse trade. Persistently infected stallions are a concern, as they shed the virus in their semen for extended periods. This poses a direct risk to breeding programs, as infected mares may abort their fetuses, causing financial losses for breeders.
Beyond individual horse health, outbreaks of EAV can lead to disruptions. Restrictions on horse movement, both domestically and internationally, are imposed to contain the virus. This affects sales, competitive events, and breeding programs, as horses and semen may be barred from entering certain countries if they test positive for the virus or antibodies. The commercial value of carrier stallions can also decrease due to expenses and complexities in managing their breeding activities.