Equine Viral Arteritis: Detection and Treatment Guide
This paper provides a clinical overview of Equine Viral Arteritis (EVA), a contagious viral disease of equids caused by the equine arteritis virus (EAV). It traces the disease's etiology from initial respiratory exposure through viral replication, vascular damage, and eventual recovery or carrier state. The paper outlines clinical signs, recommended history questions, and the laboratory testing required for accurate diagnosis, including serological and virological methods. It also addresses proper specimen collection and shipment procedures for both live animals and post-mortem samples. Finally, it discusses the absence of a specific antiviral treatment and emphasizes vaccination and biosecurity management practices for controlling the spread of EVA on equine facilities.
- Introduction to Equine Viral Arteritis: Definition, synonyms, and key symptoms of EVA
- Etiology and Pathogenesis: How EAV invades, replicates, and spreads in the body
- Clinical Signs and Case History: Observable signs and important history questions
- Diagnosis and Laboratory Testing: Lab tests and criteria for confirming EVA diagnosis
- Sample Collection and Submission: How to collect, handle, and ship diagnostic samples
- Treatment and Disease Control: No specific cure; vaccination and biosecurity practices
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What makes this paper effective
- Follows a logical clinical progression — from pathogen definition and etiology through diagnosis to management — mirroring how a practitioner would approach a disease investigation.
- Integrates authoritative veterinary sources, including the Merck Veterinary Manual and USDA outbreak reports, lending credibility to the clinical recommendations.
- Provides practical, actionable guidance on biosecurity practices and sample handling that goes beyond a purely academic description of the disease.
Key academic technique demonstrated
The paper demonstrates effective use of primary and secondary veterinary literature to build a structured clinical profile. By citing specific diagnostic thresholds (e.g., a 4-fold or greater increase in antibody titer for serological confirmation) and named laboratory assays, it shows how technical detail anchors general claims and distinguishes an informational report from a general overview.
Structure breakdown
The paper opens with a definition and overview of EVA, moves into pathogenesis, then addresses clinical presentation, diagnostic workup, specimen logistics, and finally treatment and control. This structure mirrors a standard veterinary disease factsheet format, making it well-suited for practical reference. Each section builds on the previous one, with diagnosis sections preceding sample-collection guidance in a clinically sensible order.
Introduction to Equine Viral Arteritis
Equine viral arteritis (EVA) is defined by Timoney (2019) in the Merck Veterinary Manual as "an acute, contagious, viral disease of equids caused by equine arteritis virus (EAV)." EAV is also known as Epizootic cellulitis-pinkeye, Equine typhoid, and Rotlaufseuche (Timoney, 2019). The virus can cause symptoms of fever, conjunctivitis, depression, anorexia, nasal discharge, skin rash, subfertility in stallions, death in young foals, and abortion in mares (Price, Rentsch, Burn & Spector, 1998).
Etiology and Pathogenesis
The etiology of EVA begins with respiratory exposure: the virus invades the respiratory tract, where it proceeds to duplicate itself in the tonsillar tissue and nasopharyngeal epithelium, as well as in bronchial macrophages (Timoney, 2019). Cells infected by EAV then transmit the virus to the lymph nodes, resulting in further multiplication and ultimate release into the carrier's bloodstream.
Within one week, EVA will localize in small blood vessels and panvasculitis will result. The adrenals, thyroid, and liver will also become infected. Vascular lesions, swelling, and necrosis of infected vessels will occur, setting off a chain reaction of negative effects including edema and hemorrhaging. After about a week and a half, lesions begin to repair. After approximately one month of infection, the virus is typically no longer detectable, though carrier stallions may carry the virus in their sex glands for years (Timoney, 2019).
Currently, no evidence exists that the disease can be contracted by humans, and it is hypothesized that it may also infect alpacas and llamas. Transmission between equines occurs via respiration, venereal contact, or congenitally (Timoney, 2019). EVA is not classified as a Foreign Animal Disease but does occur globally among equines. It is a reportable disease in Virginia (Virginia Department of Health, 2016).
Clinical Signs and Case History
Clinical signs include fever, dependent edema on the hind limbs, and mid-ventral edema on the stallion's scrotum and sheath (or on the mammary glands in the mare). Conjunctivitis may also be present. Nasal discharge, lacrimation, hives, and depression have been reported, though these signs are considered rare (Timoney, Creekmore, Meade, Fly, Rogers, & King, 2008).
Important history questions to ask include whether the horse has recently moved locations or come into contact with other horses, whether semen shipments were received and used, and which donors or recipients were recently present at the farm (Timoney et al., 2008).
Diagnosis and Laboratory Testing
The disease is diagnosed through laboratory testing (Timoney et al., 2008). Clinical diagnosis alone is insufficient to accurately confirm EVA. As Timoney et al. (2008) note, "presence of a neutralizing antibody titer (>1:4) to EAV in a single serum sample" is insufficient to confirm a diagnosis (p. 5). Serological confirmation requires demonstration of seroconversion or a significant (4-fold or greater) increase in antibody titer.
Applicable diagnostic tests include: virus neutralization, complement fixation, agar gel immunodiffusion, indirect fluorescent antibody, fluorescent microsphere immunoassay (MIA), and enzyme-linked immunosorbent assay (ELISA) (Center for Food Security and Public Health, 2009).
References
Center for Food Security and Public Health. (2009). Equine viral arteritis. Retrieved from http://www.cfsph.iastate.edu/Factsheets/pdfs/equine_viral_arteritis.pdf
Price, S. D., Rentsch, G., Burn, B., & Spector, D. A. (1998). The whole horse catalog: The complete guide to buying, stabling and stable management, equine health, tack, rider apparel, equestrian activities and organizations... and everything else a horse owner and rider will ever need. Simon and Schuster.
Timoney, P. (2019). Overview of equine viral arteritis. Retrieved from https://www.merckvetmanual.com/generalized-conditions/equine-viral-arteritis/overview-of-equine-viral-arteritis
Timoney, P. J., Creekmore, L., Meade, B., Fly, D., Rogers, E., & King, B. (2008). 2006 multi-state occurrence of EVA. Retrieved from
Virginia Department of Health. (2016). One health notes, 1(1). Retrieved from http://www.vdh.virginia.gov/content/uploads/sites/123/2016/12/OneHealthJan2016.pdf
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