Risk of Equine Viral Arteritis from Imported Stallions

Equine arteritis virus (EAV) causes a flu-like illness in adult horses called equine viral arteritis, and is responsible for abortion in mares and pneumonia in foals. Stallions can be become persistently infected and shed the virus in their semen. EAV is not commonly encountered in the United States but it is a significant problem in other countries. Currently, the United States has no import restrictions for EAV, which means that infected stallions can be imported for breeding purposes and thus expose resident horses.

Recently, a study was conducted in California to estimate and compare the seroprevalence of EAV in California horses and horses imported from other countries. Seroprevalence data, which provides a measure of the number of antibody-positive individuals in a population, could be used to influence legislation regarding importation laws.

Serum samples from 364 horses from 44 farms in California were compared to 226 samples from imported horses. The results indicated that only 1.9% of resident horses were seropositive for EAV, compared to 18.6% of the foreign horses (16% of which were stallions). Certain breeds appear to be more susceptible to infection with EAV, most notably warmblood types. Warmbloods are relatively uncommon in California, and other surveys have reported that 3.6% of all warmbloods in the United States are seropositive for EAV. Regardless, it is clear that importation restrictions on EAV-positive horses should be considered as a means of preventing this virus from spreading in the United States.

Journal of the American Veterinary Medical Association, 219 (7), 946-949, 2001.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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