Coggins Test for Horses: What It Is, How Long It Lasts, and What a Positive Means

A Coggins test is a blood test that checks a horse, pony, donkey or mule for antibodies to equine infectious anemia (EIA), an incurable viral disease. A veterinarian draws the blood, a USDA-approved laboratory runs it, and a negative result is the paperwork most states, shows, sale barns and boarding stables ask to see before a horse moves or arrives.

There is no single national expiry date. Depending on the state or event, a negative Coggins may be accepted for six months, twelve months, or the calendar year it was drawn in, so the date on the form matters as much as the result. Once you have it, keep a copy where you can find it at the trailer: you can save the result and a scan of the form on your horse’s free Creatures profile, and Creatures reminds you as the renewal date gets close.

This guide explains what the test looks for, how the visit and the form work, how long a result is good for, what happens if a horse tests positive, and how to keep the record so it is ready the day you need it. It is written for owners in the United States, where EIA is a federally regulated disease.

What is a Coggins test?

“Coggins” is the everyday name for an official blood test for equine infectious anemia. According to a USDA APHIS testing summary, Dr. Leroy Coggins developed an effective antibody test for the virus in 1970, an agar gel immunodiffusion (AGID) test that could identify horses carrying the virus without showing signs, and routine US testing with it began in 1972. His name stuck to the paperwork, so owners still say “pull a Coggins” whichever test the lab actually runs.

Today there are two serologic tests, as the AAEP equine infectious anemia guidelines explain:

• AGID, the original Coggins test. It is the confirmatory test.
• ELISA, which can pick up antibodies earlier than AGID but can produce false positives, so a positive ELISA is checked with AGID.

Both are official regulatory tests, and both must be run at a USDA-approved laboratory. Federal rules require any laboratory doing official testing to hold APHIS approval and to use approved methods and trained, proficiency-tested staff (9 CFR 71.22). Your veterinarian chooses which test to request on the form.

What the test does not do matters too. It looks for antibodies, and a horse needs time to make them. The AAEP notes that horses are usually negative on AGID for the first several weeks after infection and may not test positive until 60 days after exposure or later, possibly longer in donkeys and mules. A negative Coggins describes the horse on the day the blood was drawn. It is not a guarantee about the weeks since.

What is equine infectious anemia?

EIA is a viral disease of equids (horses, ponies, donkeys, mules and zebras) caused by a lentivirus. The USDA APHIS equine infectious anemia page is blunt about the two facts that drive every rule around it: there is no treatment, and infected animals that survive become carriers that can infect other equids for life. The AAEP adds that there is no approved vaccine in the US.

Signs vary widely, which is exactly why testing exists. Most infected horses show no signs at all. When signs do appear, the AAEP and APHIS describe:

• in an acute case, fever, going off feed, or sudden death;
• in a chronic case, weight loss, weakness, anemia, jaundice, and swelling of the legs, chest or belly.

If a horse, pony, donkey or mule has a fever, stops eating or seems weak and you have any reason to suspect EIA, call your veterinarian now. APHIS advises moving a suspected animal at least 200 yards away from other equids on the property while you wait. Your veterinarian decides what to test and how to treat the symptoms; this guide does not cover treatment.

How EIA spreads

The virus travels in blood. In nature it is carried mechanically on the mouthparts of large biting flies, especially horse flies and deer flies: a fly interrupted mid-meal on an infected horse finishes feeding on the next one. People spread it too. APHIS now names unclean or reused needles and syringes as the most common way EIA spreads in the United States, along with blood transfusions and blood-contaminated equipment such as IV sets, dental tools and tattoo equipment. The AAEP also lists transmission from mare to foal before birth and, rarely, through milk or semen.

EIA is not a risk to people. The AAEP states there is no evidence that it is zoonotic.

How common is it?

Rare, and largely because of testing. The 2006 APHIS summary records that the share of US samples testing positive fell from nearly 4 percent in 1972 to under 0.01 percent by 2005. In the 2024 APHIS case summary, laboratories ran 1,292,655 tests and found 147 positive horses on 63 premises, up from 61 positives on 45 premises in 2023. Cases cluster rather than spreading evenly: the same APHIS summary reports that 120 of the 147 confirmed 2024 cases were current or former Quarter Horse racehorses, where APHIS identifies spread through reused needles, syringes and IV sets, untested blood transfusions and contaminated multi-dose vials; some of those cases are tied to unsanctioned racing. Rare is not the same as gone, which is why the test is still required.

When does a horse need a Coggins test?

You will be asked for a current negative Coggins in more situations than most new owners expect.

• Crossing a state line. US Equestrian’s interstate travel guidance states that all states require a negative Coggins before a horse is transported across state lines (individual states can set exceptions, so check the destination’s rule). Most also want a Certificate of Veterinary Inspection (a health certificate), which is a separate document.
• Shows, clinics, trail rides and other events. Organizers commonly ask for it at check-in, and their window can be stricter than the state’s.
• Buying or selling. The official test form includes “change of ownership/sale” as a reason for testing, and the AAEP recommends testing any horse with an unknown or questionable EIA status, or no testing record, at purchase or when it arrives on a new premises, whatever the state rules say.
• Boarding and moving barns. Many boarding stables require a current negative Coggins before a horse arrives. Ask for the barn’s rule in writing; our guide to horse boarding contracts covers what else to check.
• Every year at home. APHIS recommends testing horses, ponies, mules and donkeys annually for EIA, even if they never leave the farm.

Size and species do not change this. A miniature horse, a donkey or a mule is an equid and needs the same test to travel. If you are pricing a small equid, our sister guide on how much a miniature horse costs counts annual vet work, including the Coggins, in the running costs.

How long is a Coggins good for?

There is no federal expiry date, and the answer depends on where the horse is going. US Equestrian notes that some states want the test dated within six months, some within twelve, and some regulate by the calendar year of the form. Events set their own rules on top. A test that is fine for a show at home may be too old for the state you are hauling through next week.

The reliable way to get this right:

1. Check the destination state. Requirements change, so go to the source: the state veterinarian’s office of the destination state, or the APHIS state and territory animal entry requirements page, which points you to each state’s agriculture department. Check any state you pass through as well.
2. Check the event or barn. Read the prize list, entry form or boarding agreement, or ask the office.
3. Plan the draw early enough. Results take time to come back from the lab, so ask your veterinarian how long their lab usually takes before you book the trip.
4. Keep the health certificate separate. A Certificate of Veterinary Inspection is a different document from the Coggins. US Equestrian says most states require one within 30 days of travel, though the timeframe varies.

When you record the result, write down the expiry that applies to how you actually use the horse, and note which rule it came from. If the form itself does not print an expiry, that is normal: the validity is set by whoever is asking for it.

How the Coggins visit and form work

The visit itself is short. Your veterinarian examines the horse, draws a blood sample, fills in the official test form, and sends the sample to an approved lab. What takes care is the paperwork, because the form has to prove that this blood came from this horse.

Under APHIS guidance on EIA testing (VS Guidance 15201.1):

• Who can draw it. Labs accept samples only from a Category II federally accredited veterinarian authorized in the state where the sample was taken, or from a state or federal animal health official. The veterinarian signs a statement that they drew the sample from the animal described.
• The form. The official federal form is VS Form 10-11. State and electronic versions are allowed if APHIS approves them and they carry the same information, so your veterinarian may send you a paper copy or an electronic one.
• What it records. The date the blood was drawn, the test requested (AGID or ELISA), the reason for testing (interstate movement, annual testing, sale, export, illness or an exposure investigation), where the horse was, the owner, and the horse’s identity: name, color, breed, age or date of birth, sex, any brand, tattoo, microchip or registration number, and a written description of markings head to hooves.
• Photos or drawings. Line drawings of markings are encouraged. Digital photos may be used if they are sharp and show at least the front, left side and right side, with no part of the horse hidden.
• Freshness. Labs must reject samples more than 30 days old, because they no longer show the horse’s current status.

Two practical tips follow from that list. First, have the horse clean, dry and easy to see on the day, with its registration papers or microchip number handy, so the description matches the horse. Second, read the finished form before you leave it in a drawer: check the name, color, markings and the date drawn. A form that does not match the horse in front of an inspector is a problem you want to find at home.

Ask your clinic what the draw, the lab fee and any farm call will cost, and whether testing several horses on one visit lowers the per-horse cost. Several horses with the same owner, location and draw date can go on one form, with individual identification for each.

What happens if a horse tests positive

A positive result is handled by animal health officials, not just your veterinarian, and the steps are set by federal and state rules. According to the AAEP guidelines:

1. The lab reports any non-negative result to state or federal animal health officials within 24 hours.
2. An official locates the horse, places it under quarantine, and draws a new sample for confirmatory testing at the National Veterinary Services Laboratories.
3. If the case is confirmed, a regulatory veterinarian investigates which horses were exposed: horses kept with or near the positive horse, horses that shared needles, syringes, dental or tattoo equipment, nursing foals, and linked horses at other barns.
4. Exposed horses are quarantined and retested 60 days after the positive horse is removed from the premises, and stay quarantined until that retest is negative.

Because an infected horse carries the virus for life, the AAEP describes two options for a confirmed positive: euthanasia, or lifetime quarantine with permanent isolation at least 200 yards from uninfected horses. Some states require euthanasia. Federal rules also require a positive horse (“reactor”) moved between states to be permanently identified with the state’s code followed by the letter A, by brand, freeze mark or lip tattoo, and allow interstate movement only to slaughter, a research facility, or its home farm under quarantine (9 CFR 75.4). Your veterinarian and your state veterinarian will explain which rules apply where you live.

If you are waiting on a result for a horse you are about to buy, wait. Do not bring a horse home on a promise that the Coggins is “in the mail”.

How to protect your horses from EIA

Prevention is mostly about blood and flies. The AAEP and APHIS recommend:

• One sterile needle and syringe per horse, every time, including a fresh needle each time you draw from a multi-dose bottle. Never share needles, syringes or IV sets between horses.
• Clean, then disinfect dental tools, tattoo equipment, surgical instruments, lip chains and bits between horses. The virus is destroyed by most common disinfectants once organic matter is washed off.
• Only licensed blood products, and transfusions only by a veterinarian.
• Control biting flies with regular stall mucking, fans, manure handled away from the barn, and fly control products; our horse fly control guide covers the options.
• Test new arrivals whose status is unknown, and isolate any horse with a fever or off feed until your veterinarian has seen it.
• Test every horse annually, as APHIS recommends.

Nothing here replaces your veterinarian’s advice on your farm’s biosecurity. If you do not yet have an equine practitioner, how to find an equine vet before you need one is worth reading before trailer season. The same visit is a good time to plan core horse vaccines, although there is no vaccine for EIA.

Keep your horse’s Coggins on its Creatures profile

The paper Coggins has a way of living in the truck that is not hitched to the trailer. A Creatures profile gives each horse one place for the result, the form itself, and a reminder before it runs out. Adding the horse is free, and the whole workflow below works on a free account.

1. Add the horse. Create the horse’s profile with its name, color, markings, date of birth and a few clear photos from both sides. This is the same identity the Coggins form describes, so it helps to have it in one place. The steps are in adding an animal to Creatures.

2. Add a Test Result record. On the horse’s Records tab, add a record and choose Test Result. For a Coggins, pick the Disease / Pathogen category and the Viral subtype, enter the Date of Report, and type the result (for example “Negative, AGID”) in Result / status. Under Expand extra fields, enter the Date of Sampling (the date the blood was drawn) and an Expiration Date. The form’s own hint says it is “For expiring results like Coggins, so renewals can be tracked”. The health and medical records guide walks through the record types.

3. Attach the form. Use Files on the same record to attach a photo or PDF of the signed test form, so the record and the document travel together. Test Result records start private, and attached files follow the record’s Make public setting, which keeps the owner’s address on the form off a public profile unless you choose otherwise.

4. Let Creatures remind you. When a test result carries an expiration date, Creatures creates a renewal reminder once that date is within 90 days, and it shows in the horse’s upcoming care. Pick the expiry from the rule you actually travel under (step 1 of “How long is a Coggins good for?” above), and set a separate booking reminder if you need the vet out earlier. Reminders and upcoming care explains how reminders work, and our article on horse test and certificate reminders covers keeping the expiry, the booking task and the new result apart.

5. Test the whole barn at once. A Test Result can be added to several animals in one save, which suits a farm call where the vet draws every horse; see applying records to a group.

6. Hand it over when the horse moves. Records travel with the horse when you transfer it to a new owner on Creatures, and you can print a record packet PDF for a new barn, a vet or a buyer; our horse record packet guide shows what to include.

Two honest limits. A Creatures record is your copy, not the official one: the signed form from your veterinarian or the lab is what an inspector or show office accepts, so carry it (or the electronic version your vet sends) when you travel. And Creatures does not decide whether a test meets a particular state’s or event’s rule; you set the expiry, so check the rule first. For the wider picture of what to keep for each horse, see horse health records.

Buying a horse? Ask for the Coggins first

A current negative Coggins is one of the first documents to ask a seller for, alongside the registration papers and any health records. Check that the name, color and markings on the form match the horse you are looking at, that the draw date is recent, and that the seller can tell you which lab ran it. If the horse has no testing record, the AAEP’s advice is to test at purchase. Our guide on where to buy a horse covers the pre-purchase exam, which is a good moment to pull a fresh Coggins.

If you are breeding rather than buying, ask the breeding farm early whether it wants a current negative Coggins on a visiting mare, and how recent. Our sister guide to the mare heat cycle covers timing a breeding.

Frequently asked questions

What does Coggins stand for?

Nothing. It is a surname. Dr. Leroy Coggins developed the agar gel immunodiffusion test for equine infectious anemia in 1970, and the test took his name.

Is a Coggins test the same as a health certificate?

No. The Coggins is a lab test for one disease. A health certificate (Certificate of Veterinary Inspection) is a veterinarian’s statement, after an exam, that the horse appears healthy and fit to travel. Interstate travel usually needs both, with different time limits.

How long does a Coggins take to come back?

It depends on the lab and how the sample gets there. Ask your veterinarian before you book travel, and build in time in case a result needs confirming.

Do donkeys and mules need a Coggins?

Yes. EIA infects all equids, and the same testing rules apply to donkeys, mules and miniature horses. The AAEP notes that antibodies may take longer to appear in donkeys and mules.

Can a horse with a negative Coggins still have EIA?

It is possible if the horse was infected recently, because antibodies can take 60 days or more to show up. That is why the AAEP advises testing new arrivals and isolating any horse with a fever until it has been checked.

Is there a vaccine for EIA?

No. There is no approved vaccine for equine infectious anemia in the United States, and no cure. Prevention and testing are the only tools.

Can people catch EIA?

No. The AAEP states there is no evidence that equine infectious anemia infects people.

Do this next on Creatures

Whether you are hauling to a show next month or just keeping the annual test straight, these are the next steps on Creatures, in the order most horse owners need them.