Merck Animal Health Reinforces Commitment to Help Protect U.S. Livestock from New World Screwworm Threat

Company underscores commitment to cattle producer and veterinarian preparedness through innovation, collaboration and education

RAHWAY, N.J., June 4, 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 reaffirmed its ongoing commitment to support the cattle industry in its response to the growing threat of New World screwworm (NWS) following confirmation of the first case in U.S. cattle, underscoring the continued need for industry-wide collaboration to combat this devastating parasite. As a leader in livestock health, Merck Animal Health has been on the forefront of developing innovative medicines for the prevention and treatment of NWS, facilitating information sharing and conversation, and providing educational resources for the livestock industry.

Our commitment to collaboration and education

As part of its proactive response, Merck Animal Health recently hosted a New World screwworm (NWS) Symposium in San Antonio, Texas. Held April 22-24, the event brought together cattle producers and veterinarians from high-risk regions, while leading researchers, academic experts, government representatives and Merck Animal Health technical team members delivered programming focused on NWS preparedness, risk mitigation and coordinated strategies to help protect U.S. livestock.

"The U.S. cattle industry had successfully eradicated New World screwworm in the past, but renewed vigilance and collaboration across the entire industry are essential to preventing and managing this evolving threat," said Rick DeLuca, president, Merck Animal Health. "Merck Animal Health is committed to being a partner in that effort by providing innovative solutions to help support veterinarian and producer preparedness."

During the NWS Symposium, experts stressed the importance of coordinated, industry-wide efforts to combat the spread and minimize risk. Because NWS can impact not just livestock but all warm-blooded animals, preparedness and strong collaboration across stakeholders are critical. Key prevention strategies highlighted by industry leaders include:
Daily observation of livestock and wildlife to detect wounds and potential infestations early
Prompt reporting of suspected cases to enable rapid response
A strong veterinarian relationship to support development of an NWS management plan

Our commitment to innovation

In December 2025, Merck Animal Health received conditional approval from the U.S. Food and Drug Administration for EXZOLT^® CATTLE-CA1 (fluralaner topical solution), the first novel ectoparasiticide introduced for beef cattle in several decades. EXZOLT CATTLE-CA1 is a pour-on product conditionally approved for the prevention and treatment of infestations caused by New World screwworm larvae (myiasis). The product has been available in the United States since early spring 2026, with distribution focused on southern border states to help ensure access in regions at the highest risk of NWS outbreak.

"Innovation plays a critical role in how we respond to emerging threats like New World screwworm," said Justin Welsh, DVM, executive director of livestock technical services, Merck Animal Health. "EXZOLT CATTLE-CA1 represents an entirely new drug class never before used in U.S. cattle. When paired with strong veterinary partnerships and proactive management, it gives the industry an important and novel tool to help protect our cattle herds."

Only EXZOLT CATTLE-CA1 EXZOLT CATTLE-CA brings a new active ingredient and drug class to the cattle industry, with no known resistance. It is the first and only topical product conditionally approved for NWS prevention and treatment and delivers the active ingredient fluralaner to act systemically1 is approved for use in beef cattle two months of age and older, and in replacement dairy heifers under 20 months. It is also conditionally approved for the treatment and control of Cattle Fever Tick.

EXZOLT CATTLE-CA1 is available by prescription in 1 L or 5 L presentations. For more information about EXZOLT CATTLE CA1, visit ExzoltCattle-CA1.com.

Photo caption: Merck Animal Health reinforces commitment to help protect U.S. livestock from New World screwworm threat with industry-wide collaboration, ongoing education, and innovations like EXZOLT CATTLE-CA1.

IMPORTANT SAFETY INFORMATION:

Conditionally approved by FDA pending a full demonstration of effectiveness under application number 141-617.

It is a violation of Federal law to use this product other than as directed in the labeling.

EXZOLT™ CATTLE-CA1 (fluralaner topical solution)

Not for use in humans. Keep out of reach of children. Accidental exposure may cause skin and eye irritation. Highly flammable. Keep away from heat, sparks, open flame or other sources of ignition. Use only for the prevention and treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis) and treatment and control of cattle fever tick (Rhipicephalus microplus) in beef cattle 2 months of age and older and replacement dairy heifers less than 20 months of age. Not for use in bulls intended for breeding 1 year of age and older, dairy calves, and veal calves. Cattle must not be slaughtered for human consumption within 98 days of treatment. For complete safety information and product dosing instructions, refer to the product label.

Product Label

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.

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