Equine viral arteritis

Equine viral arteritis is reviewed with specific reference to clinical features, etiology, transmission, diagnosis, epidemiology, and current methods for the control of this disease. There is evidence of variation in pathogenicity among strains of equine arteritis virus. Virus transmission occurs primarily by the respiratory and venereal routes during the acute phase of the infection. The long-term carrier stallion appears to play a major epidemiological role in dissemination and perpetuation of the virus. Unlike the stallion, the carrier state has yet to be demonstrated in the mare or foal. A commercial modifiedlive equine arteritis virus vaccine has been shown to be safe and efficacious for stallions and mares. The disease can be controlled by identification and isolation of carrier stallions, immunization of seronegative stallions, and by restricting the breeding of equine arteritis virus-shedding stallions to equine arteritis virus vaccinated or seropositive mares.     

Equine viral arteritis

Equine viral arteritis (EVA) can cause prominent economic losses for the equine industry. The purpose of this review is to provide the pathologist some familiarity with the clinical history, lesions, pathogenesis, and diagnosis of EVA. EVA is caused by an arterivirus (equine arteritis virus, EAV), and the vascular system is the principal but not unique viral target. EVA has variable presentations, including interstitial pneumonia, panvasculitis with edema, thrombosis and hemorrhage, lymphoid necrosis, renal tubular necrosis, abortion, and inflammation of male accessory genital glands. EAV antigen (EAVAg) can be demonstrated within the cytoplasm of epithelial cells such as alveolar pneumocytes, enterocytes, adrenal cortical cells, trophoblasts, thymus stroma, renal tubular cells, and male accessory genital gland cells. It can be also demonstrated within endothelia, in vascular, myometrial, and cardiac myocytes, macrophages, dendritelike cells of lymphoid organs, and chorionic mesenchymal stromal cells. In young and adult horses, following colonization of macrophages, the virus spreads systemically using circulating monocytes and enters the endothelium and tunica media of blood vessels, histiocytes, and dendritelike cells. Eventually, the virus multiplies within renal tubular cells. Lesions are uncommon in the aborted fetus; if present, they are mild, and EAVAg is frequently not detectable within fetal tissues and placenta. The clinical presentation and lesions of EVA may resemble those of other diseases. Complete pathologic examination associated with immunohistochemistry, virus isolation, and, especially in cases of abortion, serology will guarantee a directed and accurate diagnosis.     

Equine viral arteritis at a veterinary teaching hospital

An outbreak of equine viral arteritis (EVA) occurred at a veterinary teaching hospital in the summer and autumn of 1984. Clinical signs were observed in 16 out of 61 hospitalized horses and included ventral, limb and preputial edema, mild conjunctivitis with lacrimation, pyrexia and increased respiratory and heart rates. Of 16 clinically affected horses, 13 were undergoing experimental abdominal surgery and/or were involved in digestion experiments; 9 of the 13 were > 20 years of age. The three other clinically affected horses were client animals. Thirteen client horses developed serologic titers to equine arteritis virus in the absence of clinical signs. The risk of infection was associated with close contact, involvement in the experimental studies being conducted and length of hospitalization. The disease was mild, limited in spread and successfully controlled by quarantine.     

Equine viral arteritis — epidemiology and control

The epizootic of equine viral arteritis (EVA) in the Thoroughbred population in central Kentucky in 1984 aroused concern for a disease whose previous sporadic occurrences had gone largely unnoticed.The threat of spread of EVA through the internal movement of horses led to the imposition of considerable restrictions by other major bloodstock-raising countries on the importation of horses of all breeds from the US. Though in no way disputing the importance of spread of the EVA infection at racetracks, sales and equestrian events, etc., it has become evident that the long-term carrier stallion probably plays a major epidemiologic role in perpetuating the virus from year to year. In contrast to the stallion, the carrier state has not yet been confirmed in the mare, nor has there been any evidence of a congenitally acquired carrier state in foals.     

Equine viral arteritis (EVA): A potential trapdoor for the practicing veterinary surgeon in the United Kingdom

Equine viral arteritis (EVA) is a notifiable disease in the UK with potentially serious consequences for horse owners and breeders. Legislation exists under ‘The Equine Viral Arteritis Order 1995’ to protect the UK from this contagious equine disease. The UK is at risk of introduction of EVA through importation of infected horses or semen. There is however much misunderstanding regarding the importance of EVA and occasionally misinterpretation, specifically on how to protect and manage stallions with vaccination. Issues with changing vaccine datasheet recommendations and vaccine availability have resulted in stallions being inappropriately vaccinated or vaccinations lapsing. This article is aimed at the practicing veterinary surgeon, to update them as to the current status of EVA vaccination and disease screening in horses in the UK and how to avoid some common pitfalls.     

Equine viral arteritis: A respiratory and reproductive disease of significant economic importance to the equine industry

Equine arteritis virus is the causative agent of equine viral arteritis, a respiratory and reproductive disease that affects the members of the family Equidae. The virus was first isolated from the lung of an aborted fetus after an extensive outbreak of respiratory disease and abortion on a Standardbred breeding farm near Bucyrus, Ohio, in 1953. Since then, periodic outbreaks of equine viral arteritis have been reported in a number of countries around the world. This disease may result in significant economic loss to the equine industry due to the occurrence of abortion in pregnant mares, neonatal mortality, and establishment of the carrier state in stallions. This article provides an extensive review on equine arteritis virus, epidemiology, disease, pathogenesis, and prevention and control measures.