Neogen Corporation MARCS-CMS 731018 — September 23, 2026

WARNING LETTER

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• Delivery Method: Via Email
• Product: Animal & Veterinary; Drugs

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• Recipient: Mike Nassif; President and CEO; Neogen Corporation; 740 E Shiawassee St; Lansing, MI 48912; United States; mnassif@neogen.com

• Issuing Office: Center for Veterinary Medicine; United States

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September 23, 2026

WARNING LETTER
CMS# 731018

Re: 731018

Dear Mr. Nassif:

This Warning Letter summarizes significant violations of the Federal Food, Drug, and Cosmetic Act (FD&C Act) pertaining to Neogen Vet® HYCOAT® (Hyaluronate Sodium Sterile Solution; herein after referred to as HYCOAT®), which you distribute, and which was manufactured for you by the contract manufacturer (b)(4).

In response to a series of serious adverse events in horses, the United States Food and Drug Administration (FDA) conducted a multistate investigation. As described in more detail below, we collected samples of your product, inspected the manufacturing facility, and reviewed the epidemiological and clinical evidence associated with over 95 individual cases.

Our investigation linked significant contamination of your purportedly sterile product, HYCOAT®, to this incident, which involved the largest number of deaths in horses to be associated with a product quality defect in any FDA-regulated medical product for veterinary use. This contamination also resulted in the most fatalities in any species ever associated with a sterile FDA-regulated medical product for veterinary use.

On January 28, 2026, you recalled numerous lots of HYCOAT® (including HYCOAT® 2mL, lots 4L001 and 4L002, and HYCOAT® 10 mL, lot 5A001) due to the risk of microbial contamination.

From (b)(4), we inspected the contract manufacturer’s facility, located at (b)(4), and found HYCOAT® was manufactured under insanitary conditions, rendering the product adulterated under FD&C Act section 501(a)(2)(A).

During our investigation, we collected and analyzed samples and confirmed that HYCOAT® lot 5A001 (which purports to be sterile) was, in fact, not sterile, and is therefore adulterated under FD&C Act sections 501(a)(1) and 501(c) and misbranded under section 502(a). We subsequently reviewed HYCOAT®’s labeling and determined that the product is also misbranded under section 502(f)(1) of the FD&C Act because its labeling fails to bear adequate directions for use.

For the above reasons, the introduction of adulterated and misbranded HYCOAT® into interstate commerce violates section 301(a) of the FD&C Act, 21 U.S.C. 331(a).

You can find the FD&C Act and FDA regulations through links on FDA's homepage at www.fda.gov.

Microbiological Contamination in a Purportedly Sterile Product

Under section 501 of the FD&C Act, "A drug or device shall be deemed to be adulterated…if… its strength differs from, or its purity or quality falls below, that which it purports or is represented to possess." FD&C Act section 501(c), 21 U.S.C. 351(c). In addition, a drug or device shall be deemed to be adulterated “if it consists in whole or in part of any filthy, putrid, or decomposed substance.” FD&C Act section 501(a)(1), 21 U.S.C. 351(a).

HYCOAT® is adulterated under sections 501(c) 501(a)(1) because it is labeled as "sterile solution" but FDA's laboratory testing of HYCOAT® lot 5A001 revealed significant microbiological contamination.

FDA’s laboratory testing of HYCOAT® lot 5A001 identified the presence of viable microbiological contaminants, including the following fungal species:

- Purpureocillium lilacinum
- Paraisaria heteropoda
- Gongronella lacrispora
- Purpureocillium sodanum
- Isaria takamizusanensis

The presence of microorganisms in conjunction with your product’s labeled indications poses a high risk to patients. When used for its labeled indications (such as pressure ulcers, surgical wounds, first and second-degree burns, chronic and acute wounds, venous stasis ulcers, and autograft procedures), your product has the potential to directly contact the internal bodily tissues and/or enter the systemic circulation. Microbial contamination can cause wound infection, surgical wound dehiscence, cellulitis, tissue necrosis and, in severe cases, sepsis, which may result in death.

As you are aware, HYCOAT® is also used off-label as a joint injection.¹ It is our understanding that this off-label use represents a common manner in which veterinarians use the product in real-world medical practice, and your labeling does not contain any limitations, warnings, or contraindications pertaining to this use.² Injection of microbiologically contaminated HYCOAT® into the joint space and surrounding joint structures can cause painful lameness due to severe inflammation and infection in the joint tissues, resulting in euthanasia of some patients, particularly if the infection is refractory to treatment.

Manufacturing Under Insanitary Conditions

Under section 501 of the FD&C Act, "A drug or device shall be deemed to be adulterated…if…it has been prepared, packed, or held under insanitary conditions whereby it may have been contaminated with filth, or whereby it may have been rendered injurious to health." FD&C Act section 501(a)(2)(A), 21 U.S.C. 351(a)(2)(A).

Our inspection of your contract manufacturer's site found HYCOAT® was produced under insanitary conditions, including:

- Inadequate cleaning of manufacturing environment (no use of sporicidal agent);
- Inadequate air quality monitoring (no differential pressure monitoring);
- Inadequate environmental monitoring (no viable particulate sampling);
- Failure to conduct personnel sampling (no sampling for viable microorganisms);
- No smoke studies (no demonstration of airflow in ISO 5 area);
- Facility in poor state of repair (a (b)(4) cleanroom constructed in a warehouse with observed multiple examples of insanitary conditions and state of disrepair);
- Inadequate cleanroom gowning (exposed skin, nonsterile gowning components);
- Inadequate manufacturing process (media fills did not simulate worst-case scenario);

You failed to provide adequate quality oversight of your product’s contract manufacturer. Although you do not manufacture HYCOAT®, you distribute it under your label and are responsible for ensuring it is not adulterated or misbranded before its introduction into interstate commerce. The following are photographs taken at your contract manufacturing site. Although we note the site was not in production at the time these photographs were taken, they demonstrate the obvious uncleanliness and unsuitability of the site for producing a sterile product, which you could have easily discovered and acted upon:

Misbranding Violations

Under section 502 of the FD&C Act "A drug or device shall be deemed to be misbranded…unless its labeling bears (1) adequate directions for use.” FD&C Act section 502(f)(1), 21 U.S.C. 352(f).

HYCOAT®’s labeling lists numerous indications for which minimal to no instructions for use are given. Furthermore, many of the labeled indications are generally not appropriate for diagnosis and treatment by a layperson, and it is therefore not possible to write adequate directions for use by laypersons. These indications include:

- surgical wounds,
- chronic and acute wounds,
- autograft procedures.

Neither HYCOAT®’s label, nor its product packaging, indicates it is for use only by, or under the supervision of, a licensed veterinarian. HYCOAT®’s labeling fails to bear adequate directions for use by laypersons, and it is therefore misbranded under section 502(f)(1) of the FD&C Act.

In addition, a drug or device shall be deemed to be misbranded “if its labeling is false or misleading in any particular.” FD&C Act section 502(a), 21 U.S.C. 352(a). HYCOAT® is misbranded under section 502(a) of the FD&C Act because it is labeled as "sterile solution" but FDA's laboratory testing of HYCOAT® lot 5A001 revealed significant microbiological contamination.

Conclusion

The violations cited in this letter are not intended to be an all-inclusive list of violations that exist in connection with your products. You are responsible for investigating and determining the causes of any violations and for preventing their recurrence or the occurrence of other violations. It is your responsibility to ensure that you comply with all requirements of federal law and FDA regulations.

This letter notifies you of our concerns and provides you with an opportunity to address them. You should take prompt action to correct any violations. Failure to adequately address any violation may lead to regulatory, or where appropriate, legal action.

Within fifteen (15) working days of receipt of this letter, please notify this office in writing of the specific steps that you have taken to correct any violations. Include an explanation of each step being taken to prevent the recurrence of violations, as well as copies of related documentation. If you cannot complete corrective actions within 15 working days, state the reason for the delay and the time within which you will complete the correction. If you believe that you have complied with the FD&C Act and FDA regulations, include your reasoning and any supporting information for our consideration.

The FDA CVM, Office of Surveillance and Compliance, is encouraging electronic submission of any response you choose to submit to this letter. We encourage you to submit files up to 100 megabytes in a single email, and to divide files greater than 100 megabytes so they may be submitted as smaller files in separate emails. If you submit electronic correspondence, please ensure that your facility’s name, the CMS number at the top of this letter, and the inspection location are included in your correspondence. We intend to issue an electronic acknowledgement upon receipt of your email.

Send your electronic reply to CVM-483-Responses@fda.hhs.gov. On your communications, refer to the Warning Letter CMS# 731018 and ATTN: Juan Jimenez, juan.jimenez@fda.hhs.gov.

Sincerely,
/S/

Brett Havranek, J.D.
Acting Director
Division of Drug Compliance
Office Surveillance and Compliance
Center for Veterinary Medicine

Cc:
Linda Lou O’Connor
Director of Regulatory Affairs
Neogen Corporation
loconnor@neogen.com

Julie Geyer
Quality Assurance Manager
Neogen Corporation
jgeyer@neogen.com

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1 Among other evidence, we note that you formerly promoted HYCOAT® for this use. See, e.g., our untitled letter to you citing these claims, dated September 19, 2000.

2 During our discussion related to your recall, you objected to our consideration of off-label use of HYCOAT®, but if a common “method of administration or application” is unsafe, your product’s labeling must contain adequate warnings against that use. FD&C Act section 502(f)(2), 21 U.S.C. 352(f)(2). We noted no such warnings or contraindications in your labeling.