Mythbuster Monday: Coggins Is an Outdated Test
On Mythbuster Monday, we tackle a variety of equestrian myths to either bust or confirm. Today’s discussion: Is the Coggins test an outdated one?
It’s Mythbuster Monday, where Horse Nation dives into different equestrian myths and provides research-based evidence to either bust or confirm those myths.
Today’s Mythbuster Monday was inspired by a question that popped up on a local equestrian social media page asking whether the Coggins test is outdated. It sparked enough debate that we decided to dig deeper, look at the science and regulations behind it, and separate myth from fact. So, here it is — is the Coggins test an outdated one? Is there any modern testing that has replaced it? Does Equine Infectious Anemia remain a concern? Read on to find out!
Myth: Coggins is an outdated test
Myth or Fact: Myth
A Coggins test is a blood test used to detect Equine Infectious Anemia (EIA), a contagious viral disease that affects horses, donkeys, and mules. Named after Dr. Leroy Coggins, who developed the original testing method, the test identifies antibodies that indicate whether an equine has been exposed to the virus. Because EIA has no cure or vaccine and infected horses can remain lifelong carriers, even without showing symptoms, testing plays a critical role in protecting equine populations.
Horses that contract EIA can exhibit a wide range of clinical signs. Some experience acute episodes that may include fever, lethargy, loss of appetite, weight loss, anemia, swelling of the limbs or abdomen, and small hemorrhages on the gums or under the tongue. Others may develop chronic or intermittent symptoms, with periods of illness followed by apparent recovery. In many cases, horses become inapparent carriers, showing no outward signs at all while still capable of transmitting the virus to others.
The Coggins test is widely used as a biosecurity measure to prevent the spread of EIA, which is primarily transmitted through blood, often by biting insects or contaminated equipment. A negative test is commonly required for horses to travel, attend shows or events, be sold, or cross state and international borders. By identifying infected animals and limiting exposure, the Coggins test helps safeguard individual horses, herds, and the broader equine industry.
But, is it an outdated test?
A University of Kentucky article explains that while the Coggins test (AGID), developed in the 1970s, remains the gold standard and regulatory backbone of EIA screening, researchers are studying ways to improve diagnostic accuracy by combining multiple tests. The article notes that newer enzyme-linked immunosorbent assay (ELISA) tests can detect some EIA cases that the Coggins test alone may miss, especially in carriers with low antibody levels. In controlled comparisons, a three-tiered approach using ELISA first, followed by Coggins confirmation and immunoblot testing when results differ, identified up to 20% more EIA cases than Coggins testing alone.
Importantly, the study reinforces that the Coggins test continues to be a central component of EIA surveillance due to its specificity and regulatory status: it is still widely required for interstate movement, event participation, and disease monitoring. Even as researchers refine and supplement testing strategies with ELISA and immunoblot methods, the Coggins test’s role in confirming positive results and serving as an official diagnostic tool persists.
Rather than being obsolete, the Coggins test remains essential in modern EIA control efforts and current research aims to enhance its effectiveness through integrated testing protocols rather than replace it entirely.
An article published by The Horse highlights that EIA continues to be a global health issue, with infection levels rising in parts of Mexico, South America, and even reported in regions of the southern United States and northwestern Canada. Because EIA has no cure or effective vaccine and remains a lifelong infection once contracted, ongoing disease surveillance and testing are essential to identify carriers and prevent further spread.
The report emphasizes that Coggins tests (AGID) and rapid ELISA tests are required in most countries when horses are transported, compete, or change owners, showing that blood testing is still the primary tool used worldwide to monitor and control the disease. The World Organization for Animal Health (WOAH) has designated EIA a notifiable disease, reflecting its recognized importance in global equine health.
It also points out that EIA often goes undetected without testing because infected equids can be asymptomatic carriers for years, underscoring why routine testing, including the Coggins test, remains crucial for biosecurity and animal health. Rather than being obsolete, surveillance efforts like the Coggins test remain relevant because EIA is still present around the world, can spread quietly, and has serious implications for equine populations when not monitored.
The TrailTalk article from Kansas State University’s Veterinary Health Center reinforces why testing remains an important disease-control tool. Beginning in January 2025, the Kansas Department of Agriculture now requires all horses used for exhibition — whether traveling from another state or already within Kansas — to have a current negative Coggins test dated within the last 12 months. Additionally, horses changing ownership must also have a negative test before transfer. Valid Coggins tests are documented on the official USDA VS Form 10-11, and sellers must provide the certificate to new owners when transferring a horse.
The article lays out why Coggins testing continues to be vital: EIA is a viral infection with no effective vaccine or cure that causes fever and anemia, and infected horses remain lifelong carriers capable of spreading the virus to other equids. Horses testing positive must either be isolated under strict quarantine or euthanized under regulatory oversight.
It also highlights how testing has dramatically reduced disease prevalence over time: while roughly 4% of horses tested positive for EIA in the early 1970s, today less than 0.004 % of tests are positive nationally, a result attributed to sustained surveillance and testing efforts. Despite the low incidence, outbreaks still occur in clusters, showing that disease risk has not disappeared.
The article explains that two serological tests are acceptable for detecting EIA, the traditional Coggins test (agar gel immunodiffusion) and a faster ELISA option, both of which are performed in USDA-approved labs. Horse owners are encouraged to test annually so they are prepared with current results for travel or events.
These sources collectively debunk the myth that the Coggins test is outdated or no longer necessary. Across veterinary research, regulatory guidance, and global disease surveillance, a consistent theme emerges: Equine Infectious Anemia remains a present-day risk, and reliable testing is still essential for protecting horse populations. The sources make it clear that the Coggins test continues to serve as a cornerstone of EIA control because the disease has no cure or vaccine, infected horses can be lifelong carriers without visible symptoms, and testing is often the only way to identify and contain infection. Far from being obsolete, the Coggins test remains a critical biosecurity tool that supports responsible horse movement, disease prevention, and the long-term health of the equine industry.
Do you have an equine myth you’d like us to tackle? If so, send it our way! Email your suggestions to [email protected]. Put Mythbuster Monday in your subject line.
