What is a Coggins test, and how long is it good for?

A Coggins test is a blood test that shows your horse is negative for equine infectious anemia (EIA). You need a negative result to take a horse across state lines, and most shows, many sales and many boarding barns ask for one too. Most states accept a test drawn within the past 12 months, but some places want one from the past 6 months, so always check the destination state and event.

What is equine infectious anemia?

EIA is a viral disease of horses, ponies, donkeys, mules and zebras. There is no treatment and no vaccine. USDA APHIS says it poses no threat to people, but it is a reportable disease in every state.

The virus lives in the blood. Biting flies, especially horse flies and deer flies, carry it from horse to horse. People spread it too, through reused needles and syringes, transfusions from untested donors, and dental or tattoo tools that weren’t cleaned between horses. APHIS calls this human-caused spread the most common route in the US today.

A sick horse may run a fever, go off feed, lose weight or get swollen legs, and some die suddenly. But the AAEP notes that most infected horses show no signs, and every infected horse carries the virus for life. You can’t spot a carrier by looking, which is why testing matters.

EIA is rare. In 2024, US labs ran 1,292,655 EIA tests and found 147 positive horses. APHIS tied 120 of them to current or former Quarter Horse racehorses infected through practices like reused needles and blood from untested donors.

What a Coggins test is

The test is named after Dr. Leroy Coggins, who developed it in 1970. Its formal name is the agar gel immunodiffusion (AGID) test. It looks for antibodies to the EIA virus, and the result is either negative or positive.

Labs can also run a second USDA-approved test, the ELISA, and the paperwork is still usually called your Coggins. The differences:

Speed: at the lab, an AGID takes a few days and an ELISA can be done in a few hours, according to Kansas State University’s Veterinary Health Center.
Sensitivity: the ELISA can pick up antibodies earlier than the AGID.
Confirmation: the ELISA can give false positives, so a positive result is confirmed with an AGID.

Your vet chooses which test to request. Neither catches a brand-new infection: on the AGID, horses usually test negative for the first 2 to 3 weeks, and rarely for 60 days or longer. A negative result describes your horse on the day the blood was drawn, which is why it expires.

How the test is done

A vet draws blood. It must be a federally accredited veterinarian, who certifies on the form that they drew the sample themselves.
The vet fills out the paperwork. The official form is USDA’s VS Form 10-11, on paper or electronic. It records the owner, where the horse lives and a detailed description: color, breed, age, sex, any microchip, tattoo or brand, and every permanent white marking, scar and whorl. Paper forms often include a drawing.
Electronic forms use photos. Kansas State’s vets note that most Coggins tests are now done electronically, with photos. Take blankets off and hose off muddy legs so the markings show.
An approved lab runs the test. About 400 labs are approved for EIA testing, and any positive is confirmed by the National Veterinary Services Laboratories.

The date that counts is the day the blood was drawn. The form calls it the official test date.

How long is a Coggins good for?

Most states accept a negative test from the previous 12 months. Oregon, Pennsylvania, South Carolina and Texas all do for horses entering the state.

It isn’t universal, though. The US Equestrian Federation (USEF) says some states require a test dated within six months or 12 months, and others go by the calendar year of the form. For example:

Texas lets horses enter for shows on an equine interstate passport only with a negative test from the previous six months.
Canada wants a negative test from the previous six months for horses coming from the US.
Shows, sales and barns can set their own rules on top of state law.

Before any trip, check the destination state’s entry rules (your vet or the state veterinarian’s office can tell you) and the event’s requirements.

When you’ll need one

Crossing state lines. USEF says all states require a negative Coggins for interstate travel.
Shows and events. The Equine Disease Communication Center notes that many events require a negative Coggins within 12 months to enter the grounds. Some states require one even if you never leave the state: Kansas now does for every horse used for exhibition, and South Carolina for any “public assembly” of horses from different owners, including shows, trail rides and boarding stables.
Sales. Texas and Kansas require a negative test from the previous 12 months when a horse changes owners. The AAEP advises asking for proof of a recent negative test at purchase.
Boarding barns. The AAEP recommends barns ask every new horse for proof of a recent negative test, and Penn State Extension notes that most equine facilities want one.

Many states exempt nursing foals traveling with a mare that tested negative, but the age cutoff differs: under 6 months in Oregon, under 8 months in Texas.

Coggins vs. health certificate

A health certificate, or Certificate of Veterinary Inspection (CVI), is a separate document. An accredited vet examines your horse, confirms its identity and certifies that it is fit to travel. States typically require one for horses coming in.

	Coggins test	Health certificate (CVI)
What it shows	Negative for EIA on the day blood was drawn	Horse was examined and fit to travel
How it’s done	Blood sample sent to an approved lab	Exam by an accredited vet
Usually accepted for	12 months (6 in some places)	30 days (varies by state)
When you need it	Travel, shows, sales, many barns	Mostly for crossing state lines

USEF says most states require a CVI within 30 days of travel, though the window varies. Utah State University Extension adds that a standard CVI covers a single destination, and that during a disease outbreak states may want one issued within 72 hours of shipping.

If you travel often, ask your vet about an Extended Equine Certificate of Veterinary Inspection (EECVI): a digital health certificate valid for six months, where you log each trip online. North Dakota counts 33 participating states, so confirm your destination accepts it.

What happens if a horse tests positive

The lab reports a positive result to state or federal animal health officials within 24 hours. An official quarantines the horse and takes a new sample to confirm it. Horses that lived nearby or shared equipment are quarantined and tested, then retested 60 days after the positive horse is removed.

A confirmed positive horse is infected for life. The options are euthanasia or lifelong quarantine at least 200 yards from other horses. Under federal rules, a positive horse is permanently marked with a brand, freeze mark or lip tattoo ending in “A”, and can cross state lines only in narrow cases, such as going to slaughter. State rules add more detail.

Practical tips

Know the expiry date. Note the date the blood was drawn and when the test runs out, including the six-month date if you’re heading somewhere stricter.
Book before show season. March, April and May are the busiest months for EIA testing, according to APHIS. You can ask for the blood draw at the spring vaccine visit; see our horse vaccination schedule.
Check the form right away. Make sure the name, markings and microchip number match your horse. Labs can fix small errors only for a limited time; bigger problems can mean a new blood draw.
Keep it with you. Carry the paperwork when your horse travels, and keep a copy on your phone for the show office or a new barn.
Help prevent EIA. Use a new needle and syringe for every horse, and control flies.

Equiny stores the Coggins in your horse’s documents vault, reminds you before it expires and lets you share it with your barn. For the rest of the yearly calendar, see our horse care checklist.

Frequently asked questions

How long is a Coggins test good for?

Usually 12 months from the day the blood was drawn. Some states, events and Canada want one from the past six months, so check before you travel.

Do I need a Coggins for a horse show in my own state?

Often, yes. Many shows require a negative test within 12 months, and some states, such as Kansas and South Carolina, require one at shows even for horses that never leave the state.

What is the difference between a Coggins and a health certificate?

A Coggins is a blood test showing your horse is negative for EIA, usually accepted for 12 months. A health certificate (CVI) records a vet’s exam and is usually valid for 30 days. Crossing state lines usually takes both.

Is an ELISA the same as a Coggins?

Both are USDA-approved blood tests for EIA antibodies. The classic Coggins is the AGID test. The ELISA gives results faster, and a positive ELISA is confirmed with an AGID.

Sources

This guide is general information, not veterinary advice. Ask your vet about your own horse.