EIA and Coggins Test Requirements in Texas: What Every Horse Owner Must Know

If you own, sell, or transport horses in Texas, understanding the state’s Equine Infectious Anemia (EIA) testing rules is not optional — it is a legal requirement enforced by the Texas Animal Health Commission (TAHC). A Coggins test is a blood test used to detect EIA, a serious and potentially fatal viral disease in horses, and because there is no cure for EIA, strict testing requirements are enforced nationwide.

Texas has some of the most clearly defined equine health regulations in the country, covering everything from routine ownership transfers to interstate travel and disease response. Whether you are a seasoned horse owner or new to equine care, knowing exactly when a test is required, how to get one, and what happens if a horse tests positive can protect your animals, your property, and your legal standing.

Pro Tip: Always keep your horse’s original Coggins paperwork on hand during transport. The test document — commonly called “Coggins papers” — serves as official proof of testing, and equine owners should keep it on hand when traveling with the horse.

What Is Equine Infectious Anemia (EIA) and Why It Is Regulated in Texas

EIA is a blood-borne viral disease of equids caused by the Equine Infectious Anemia Virus (EIAV), a lentivirus in the Retroviridae family, making it a relative of HIV. The virus belongs to the same broad family as HIV, which helps explain why it integrates into host cells and cannot be cleared by the immune system.

EIA is a viral disease spread by insect bites and poor hygiene practices, contaminated needles, and other instruments. It spreads primarily via blood-feeding insects like horseflies and deerflies, as well as contaminated equipment such as needles and surgical tools. Any shared instrument that contacts blood can carry the virus from one animal to another.

Clinical signs of EIA vary widely. Some horses show no outward signs of disease. Others may experience acute episodes characterized by fever, weakness, anemia, jaundice, and edema. Chronic cases may show intermittent fever, weight loss, or poor performance. The inapparent carrier form is particularly dangerous because horses with no visible signs remain contagious, and once infected, a horse is a lifetime carrier, posing a threat to other equines.

There is no cure or vaccine for EIA, making testing critical for disease prevention and control. Texas regulates EIA aggressively because a single positive animal on a shared property can trigger herd-wide quarantine. In 2024, TAHC received positive EIA confirmations for more than 70 equines in counties across Texas, and through epidemiological and disease investigations, it was determined that a majority of these cases were iatrogenically transmitted, or human-facilitated transmissions.

Which Animals Require a Coggins Test in Texas

The official tests for equine infectious anemia in Texas apply to horses, asses, mules, ponies, zebras, and any other equine in Texas. The rule is broad by design — any member of the equid family falls under TAHC’s testing authority.

Equine include horses, mules, asses, ponies, and other members of the horse family. For exotic equine such as zebras, separate movement requirements apply under the Exotic Livestock and Ratite Movement rules. If you are unsure whether your animal qualifies, contact the TAHC directly at 1-800-550-8242.

There are limited exemptions. A negative EIA test within the previous 12 months is required for all equine, except zebras, which are eight months of age or older, changing ownership in Texas, except if the animal is sold to slaughter or is a nursing foal transferred with its dam when the dam has tested negative during the 12 months preceding the date of transfer. Outside of those narrow exceptions, all equids of applicable age must be tested in the circumstances described below.

Key Insight: Nursing foals under eight months of age traveling with a dam that has a current negative test are generally exempt from testing requirements. Once a foal reaches eight months, standard testing rules apply.

When a Coggins Test Is Required in Texas

Texas law ties the Coggins test requirement to specific triggering events rather than a blanket annual mandate for every horse on private property. Knowing those triggers keeps you compliant without unnecessary testing.

• Change of ownership: Equine animals must have a negative EIA (“Coggins”) test upon change of ownership, and the results must be accompanied by a completed VS Form 10-11 (official Equine Infectious Anemia Laboratory Test document) for each horse.
• Shows, fairs, and public assemblies: Equine animals that participate in shows, fairs, exhibitions, or assemblies such as rodeos, barrel racing, or trail rides must have a Coggins test within the last 12 months.
• Interstate entry into Texas: Horses must have proof of a negative Coggins test within 12 months, and these rules apply to horses entering Texas from another state and are often required for in-state activities such as shows, exhibitions, or sales.
• Proximity to another owner’s equine: TAHC has enacted a regulation that requires equids to have had a negative blood test for EIA within the previous 12 months if the animals are kept within 200 yards of equids owned by another individual.
• Pari-mutuel tracks: Equine entering a pari-mutuel racetrack must meet additional CVI and EIA documentation requirements under TAHC Rule §49.1(r).

The 12-month validity window is the standard across all these triggers. In general, Coggins papers are valid for up to one year; however, some states or shows may require a negative Coggins test within six months of the event or transportation. Always confirm specific event requirements with the organizer before you travel.

How the Coggins Test Works and Approved Testing Methods in Texas

Testing is performed to determine if a horse has been exposed to the virus and has produced an antibody response. This type of testing is often referred to as Coggins testing, named after Dr. Leroy Coggins, a virologist who developed the test for EIA. Leroy Coggins developed the EIA serological test in the early 1970s, and by 1975, more than 10,000 horses, representing about 4 percent of those tested, were found to be positive.

Texas recognizes two primary approved testing methods. The Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) offers two methods of detecting EIA antibodies: an agar gel immunodiffusion (AGID) method and an enzyme-linked immunosorbent assay (ELISA). Each method has a distinct role in the regulatory process.

Test Method	Common Name	Role in Texas Regulations	Key Characteristic
Agar Gel Immunodiffusion (AGID)	Coggins Test	Regulatory gold standard; used for official certification	High specificity; detects EIAV-specific antibodies
Competitive ELISA (CELISA)	ELISA / Coggins	Approved for official testing; suitable for high-volume screening	High sensitivity; rapid turnaround

The ELISA test offers high sensitivity and rapid turnaround, making it well suited for high-volume screening; however, any ELISA-positive sample must be confirmed by AGID testing in accordance with USDA and state regulations. This two-step confirmation process prevents false positives from triggering unnecessary quarantine actions.

The testing process itself follows a strict chain of custody. Only USDA-approved laboratories, including USDA-approved off-site laboratories, are allowed to run the AGID and CELISA or other USDA-licensed tests, and only test samples from accredited veterinarians or other TAHC-authorized personnel accompanied by a completed VS Form 10-11 can be accepted for official testing.

During the appointment, your veterinarian will give your horse a thorough physical examination and complete an EIA form that includes details such as your horse’s coloration, markings, age, and breed, along with digital images. A blood sample is then taken and submitted to an accredited lab for analysis along with the EIA form and the images.

A negative test result means no antibodies were detected — the horse is either uninfected or was exposed so recently that antibodies have not yet developed. After potential exposure, TVMDL recommends repeating the test at 60 days. You can learn more about EIA testing procedures through Texas A&M AgriLife Extension.

Important Note: As of January 1, 2026, all import certificates of veterinary inspection (CVIs) must be electronic. Confirm with your veterinarian that documentation is submitted through an approved digital platform before any interstate movement.

Interstate Movement and Import Requirements in Texas

Moving horses across state lines into Texas involves a layered set of requirements that go beyond the Coggins test alone. In addition to meeting Texas Coggins requirements, horses entering Texas must also have a Certificate of Veterinary Inspection (CVI). This document must be issued by a licensed and accredited veterinarian and completed within 30 days of travel.

For interstate travel into Texas, both a valid CVI and proof of a negative Coggins test are required. The CVI must include accurate identification details that match the horse and its Coggins test. Mismatched documentation is one of the most common causes of delayed or rejected entry at state borders.

Frequent travelers have an alternative option. Texas participates in the 6-month Extended Equine Certificate of Veterinary Inspection (EECVI) program. This option allows eligible horses that travel frequently between participating states to use a single certificate for up to six months, rather than obtaining a new CVI for each trip. The EECVI must still be accompanied by a current negative Coggins test and is subject to specific enrollment and usage requirements.

For horses being sold and brought into Texas, the requirements are explicit. Equine intended for sale in Texas must have a valid CVI and current EIA test prior to entering the state. Texas requires all equine entering Texas to obtain a valid CVI and EIA test (Coggins) prior to entry. Contact the TAHC permits department at 512-719-0777 for specific permit guidance before moving horses across state lines.

For intrastate movement within Texas, equine are not generally required to obtain a certificate of veterinary inspection (CVI), though EIA testing rules still apply for ownership changes, events, and proximity situations described in the previous section. If you enjoy equine activities in Texas, you may also find our guide to the fastest horse breeds an interesting read.

What Happens When a Horse Tests Positive in Texas

A positive EIA result sets a mandatory regulatory process in motion immediately. A reactor is any equine that discloses a positive reaction to the official test. The individual collecting the test sample must notify the animal’s owner of the quarantine within 48 hours after receiving the results.

Owners who receive a positive result do have a narrow window to request a retest. Equine disclosed as reactors may be retested prior to branding, provided owners or their agents initiate a request to the TAHC Area Director of the area where the horse is located, retests are conducted within 30 days after the date of the original test, and blood samples for retests are collected by the person who collected the sample for the first test or by TAHC personnel and submitted to the Texas Veterinary Medical Diagnostic Laboratory (TVMDL) for testing.

If the positive result is confirmed, permanent identification follows. Unless euthanized, all confirmed positive equine must be identified with a “74-A” freeze or firebrand on the upper left shoulder or neck within 10 days. Texas horses that test positive for EIA are permanently identified with a “74A” brand on their left shoulder. This branding ensures the animal can never re-enter the general horse population without detection.

Once branded, a reactor’s movement options are severely restricted. Following official identification, a reactor must be accompanied by a VS Form 1-27 permit issued by an accredited veterinarian or other authorized state or federal personnel when moved from its home premises, either directly to a slaughter plant, slaughter-only market, or slaughter-only buying facility, or directly to an approved diagnostic or research facility.

You can review the full official rule text at 4 Tex. Admin. Code § 49.1 via Cornell Law’s Legal Information Institute.

Quarantine, Euthanasia, and Isolation Rules in Texas

Any equine animal found to be a reactor to the official test will be quarantined by a representative of the Texas Animal Health Commission to the premises of its home, farm, ranch, or stable until natural death, disposition by euthanasia, slaughter, or disposition to a TAHC-approved diagnostic or research facility.

The quarantine does not affect only the positive animal. If an equine tests positive, all equine animals on the shared premises, or otherwise exposed to the EIA-infected animal, will be placed under quarantine by the TAHC, and all equine must be tested. Quarantines are released at the time TAHC requirements are met.

The 200-yard rule is a cornerstone of Texas EIA containment. The quarantine restricts the infected equine, all other equine on the premise, and all equine epidemiologically determined to have been exposed to an EIA-positive animal to isolation at least 200 yards away from equine on adjacent premises. This distance requirement is based on the flight range of the biting insects that transmit the virus.

Whole-herd testing is mandatory when a reactor is identified. All equine except nursing foals that are part of a herd from which a reactor has been classified shall be tested by an accredited veterinarian at the owner’s expense or by Commission personnel. The owner bears the cost of this testing.

Quarantine release follows a specific timeline. The EIA quarantine may be released by the Texas Animal Health Commission after all quarantined equine test negative at least 60 days following identification and removal of the last EIA-positive equine. Epidemiological data may be considered in the release of the quarantine.

Horses confirmed positive can be quarantined for the rest of their life but are usually euthanized. Because there is no cure or vaccine, infected horses are considered infectious for life, and regulations require that positive horses be permanently quarantined, euthanized, or transferred to an approved research facility.

Exposed equine that are permitted to move face their own identification requirements. Exposed equine must be identified with an “S” brand placed on the left shoulder or left side of the neck, and be accompanied by a VS Form 1-27 permit issued by an accredited veterinarian or other authorized state or federal personnel when moved.

For more on animal health regulations in Texas, see our guide to rabies vaccine requirements in Texas and our overview of fishing license requirements in Texas.

Penalties for Non-Compliance in Texas

Failing to comply with TAHC’s EIA and Coggins test rules carries real consequences — for your animals, your operations, and your finances. Failure to provide valid Coggins documentation can result in denied entry, fines, or quarantine. At events and state entry points, horses without current documentation may be turned away immediately.

The TAHC operates a formal complaint and enforcement process. TAHC makes an initial assessment of complaint details to determine if there is a violation of a Commission rule. If a violation has occurred, TAHC will take appropriate actions to remedy the problem and prevent further violations, as detailed in the Texas Agriculture Code. Enforcement authority is grounded in Title 6, Subtitle C, Control of Animal Diseases and Pests, Chapters 161 through 168 of the Texas Agriculture Code.

Beyond fines, non-compliance can trigger broader regulatory action. Animals that have been exposed to a disease may be restricted from movement to other premises. TAHC will issue a “Hold Order” to restrict movement of animals suspected of exposure to a disease. A “Quarantine” is used to restrict movement of known positive animals. A Hold Order or Quarantine can effectively shut down all equine movement on your property until compliance is restored.

Selling a horse without the required EIA documentation is a specific violation. A negative EIA test within the previous 12 months is required for all equine eight months of age or older changing ownership in Texas. Any equine sold through a market that has not had a negative EIA test in the twelve months preceding the date of sale must be permitted for movement.

Important Note: To report a suspected TAHC violation, you can contact the Commission by phone at 1-800-550-8242, by email at tahc-complaints@tahc.texas.gov, or through the TAHC online complaint portal. Within ten working days of receipt of the complaint, TAHC will send an acknowledgement of receipt to the complainant and then make an initial assessment to determine if there is a violation of a Commission rule.

Staying compliant is straightforward when you plan ahead. Schedule your horse’s EIA test well before any ownership transfer, event entry, or interstate trip. Work only with USDA-accredited veterinarians, ensure all paperwork uses the official VS Form 10-11, and store digital copies of your Coggins certificates through an approved platform. EIA can be prevented with routine testing and careful biosecurity practices, and by performing annual tests, veterinarians help protect the equine community. Compliance protects not just your horses, but every animal in the broader Texas equine community.

For more information on Texas wildlife and animal regulations, explore our articles on types of insects in Texas and types of bats in Texas. You can also review the official TAHC Equine Movement Summary and the TVMDL’s detailed EIAV resource for further regulatory guidance.