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Minimizing the Risk of EIA

Risk Factors

These factors can put horses at greater risk for contracting EIA:

  • close proximity to regions where EIA outbreaks have occurred

  • environments with a steady influx of new horses, especially if negative Coggins certificates are not required

  • exposure to horses at shows, sales or other events where health care regulations are not enforced and a negative Coggins certificate is not required pastures in damp, swampy areas where insects are abundant

EIA is diagnosed by testing a horse’s blood sample. The original test was developed by Dr. Leroy Coggins in 1970 and is known as the Coggins test or the agar gel immunodiffusion (AGID) test. This test consistently and reliably detects the presence of EIA-specific antibodies in the blood. A positive test indicates a horse is infected and carries the EIA virus. Positive tests are redone several times to guarantee their accuracy. Currently an Enzyme Linked Immunoadsorbent Assay (ELISA) test is used, as it provides faster results. Positive tests are then confirmed with the older Coggins test.

Control Measures

Good management principles and control measures can reduce the risk of EIA infection in your horses. The following guidelines will help:

  • Test all horses for EIA annually. Horses at greater risk should be tested every 4-6 months.

  • Farm owners and operators should require and verify a current negative Coggins certificate before introducing any new horses to the farm or ranch.

  • Quarantine new horses for 45 days and observe them for any signs of illness before introducing them to the herd. Retest them if EIA exposure is suspected.

  • Horse show and event managers should require and verify negative Coggins certificates for all horses entering the premises.

  • Use only one disposable needle or syringe per horse when administering vaccines or medications.

  • Sterilize dental tools before using them on another horse.

  • Keep all stable areas clean, dry and waste-free. Practice good pasture management techniques such as removing manure and providing adequate drainage to discourage breeding sites for pests.


CAHSS Equine Network