DIAGNOSIS
The most common and internationally accepted test for equine infectious anemia virus is the agar gel immuno-diffusion test (Merck Veterinary Manual 2012). It is also known as a Coggins test as it was Dr. Leroy Coggins who created it as a useful means of detecting EIAV antigens in a horse (AAEP undated). This test will detect antigens in horses regardless of their disease status, clinical or subclinical. The test must be done by Canadian Food Inspection Agency accredited labs and the blood sample taken by your private veterinarian (CFIA 2013). Your veterinarian must also fill out a document required for the test with his or her signature. The test has to have been done within 6 months of export of the horse if crossing the border (CFIA 2013). The test requires at least 24 hours turnaround time and results are usually received by the owner within 1-2 days (Idexx Labs undated).
A second option is and C-ELISA test for antibodies from a blood sample. This can be done on-farm and is completed within about one hour, however all positive tests are required to be confirmed by a Coggins test to ensure no false positive results (AAEP undated). The sensitivity is said to be higher for this test than the Coggins, meaning that negative results are likely trustworthy with the ELISA alone (Merck Veterinary Manual 2012). One thing to be cautious of when testing foals is that a suckling foal may falsely test positive on ELISA due to antibody transfer via colostrum from the mare (for up to 6-8 months after obtaining the antibodies) and it should be confirmed whether or not the foal is truly infected with the virus by a Coggins test (AAEP undated).
A second option is and C-ELISA test for antibodies from a blood sample. This can be done on-farm and is completed within about one hour, however all positive tests are required to be confirmed by a Coggins test to ensure no false positive results (AAEP undated). The sensitivity is said to be higher for this test than the Coggins, meaning that negative results are likely trustworthy with the ELISA alone (Merck Veterinary Manual 2012). One thing to be cautious of when testing foals is that a suckling foal may falsely test positive on ELISA due to antibody transfer via colostrum from the mare (for up to 6-8 months after obtaining the antibodies) and it should be confirmed whether or not the foal is truly infected with the virus by a Coggins test (AAEP undated).