Merck Animal Health Announces FDA Approval of EXZOLT™ (fluralaner oral solution) for Chickens, the First Systemic Treatment for Northern Fowl Mites

Innovative oral solution offers a safe and effective approach to combat northern fowl mite infestations in poultry

RAHWAY, N.J., July 18, 2025 – Merck Animal Health, known as MSD Animal Health outside of the United States and Canada, a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE:MRK), today announced the U.S. Food and Drug Administration (FDA) approval of EXZOLT^™ (fluralaner oral solution), a parasiticide for chickens that treats and controls northern fowl mites (Ornithinyssus sylviarum) in production houses.

EXZOLT is proven to be safe for laying hens and replacement chickens. This first-of-its-kind product, based on the fluralaner molecule, treats northern fowl mite infestations by targeting the parasite’s nervous system and killing mites that have taken a blood meal while remaining safe for the host animal.

“Northern fowl mites pose a significant threat to poultry, leading to increased stress levels, reduced weight gain and diminished egg quality and production in affected birds. They are also a major source of economic loss for layer and pullet operations,” said Jim Stockam, D.V.M., poultry technical services at Merck Animal Health. “We are proud to introduce Exzolt to the U.S. poultry industry as part of our commitment to The Science of Healthier Animals^®.”

Conveniently administered in drinking water, EXZOLT reduces stress associated with other treatment methods and minimizes exposure to chemical sprays for both workers and birds.

“EXZOLT is more impactful than traditional spray products for rapidly and dramatically decreasing infestation burdens,” adds Stockam. “With a zero-day withdrawal period, eggs from chickens treated with EXZOLT are safe to consume, making it ideal for maintaining the health, performance and welfare of flocks. The meat withhold period is 11 days.”

EXZOLT is available in 1 L or 4 L presentations. For more information about EXZOLT, contact your Merck Animal Health sales or technical services representative or visit https://www.merck-animal-health-usa.com/species/poultry.  

IMPORTANT SAFETY INFORMATION: EXZOLT™ (fluralaner oral solution)

Not for use in humans. Keep this and all drugs out of the reach of children. Accidental exposure may cause skin and eye irritation. Accidental ingestion may cause gastrointestinal disturbances and hypersensitivity reactions in humans. Chickens must not be slaughtered for human consumption for 11 days after the last treatment. No egg discard is required when used according to the labeling. For complete safety information and product dosing instructions, refer to the product label.

Product Label

Merck Animal Health announces FDA approval of EXZOLT^™ (fluralaner oral solution), a parasiticide for chickens that treats and controls northern fowl mites (Ornithinyssus sylviarum) in production houses.

About Merck Animal Health

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than a century, we’ve been at the forefront of research, bringing forward medicines, vaccines and innovative health solutions for the world’s most challenging diseases. Merck Animal Health, a division of Merck & Co., Inc., Rahway, N.J., USA, is the global animal health business of Merck. Through its commitment to The Science of Healthier Animals^®, Merck Animal Health offers veterinarians, farmers, producers, pet owners and governments one of the widest ranges of veterinary pharmaceuticals, vaccines and health management solutions and services as well as an extensive suite of connected technology that includes identification, traceability and monitoring products. Merck Animal Health is dedicated to preserving and improving the health, well-being and performance of animals and the people who care for them. It invests extensively in dynamic and comprehensive R&D resources and a modern, global supply chain. Merck Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit www.merck-animal-health.com and connect with us on LinkedIn, Facebook, X (formerly Twitter) and Instagram.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

            This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the company’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

            Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

            The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2024 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

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